The Stovebolt Site Forums The Shop Area Engine Shop Gas Tank Sending Unit -now fuel delivery problem

55.2 235 i6 12V
Fuel getting to the fuel pump problem.

New fuel tank with this new sending unit.

For now: fuel line goes straight from the sending unit connection to the fuel pump, but I can't get it to get fuel there. Removed from the engine, the pump works fine. It took longer than usual for fuel to get there, however- I know the pump's pressure ratings. The lines are clean. The sending unit is a fresh new install, and there was nothing in the new tank. Filler neck, gas cap, & hoses also new. These parts were sold together, as a kit.

I have a good supply of fuel when the engine got to running for the run-in last week. I disconnected the fuel line from the fuel pump intake side & back-pumped (?) the line with air.
This got fuel pumping fine, but that is not ideal to do every time.

Thank you for any advice on how to check this out.

Brad

Do you have a little filter/sock on the opening of the pick-up line/tube in the tank? Could that opening be getting clogged from gunk in the bottom of the fuel tank?

It's a new tank- actually everything is new. I cleaned out the portable tank prior to getting the gas, as well.

There is a sock filter on the end of the pick-up tube (down in the tank).

Working on assumption that it is not ____? I guess it could turn in on itself. I'm yet to remove the new sending unit from the tank.

Brad

Does the fuel pump a check valve thats gone bad, letting air into the system from the carb and running back through the pump to the tank?

Did you check the output side of pump for flow while cranking? I would not back blow air. Are there any filters in system? The pump flow test will tell all. When you say "This got fuel pumping fine" what are you going by to say that? The only way to check flow is run the output line into a container while cranking motor.
1. You don't say if it is a new pump.
2. You don't say that your problem is motor won't start.
3.Lets start with what your problem is, then figure out what's wrong.
You can ONLY check a pump ON the motor. You can tell nothing by looking at the input side. Please advise that motor won't start, won't stay running, won't idle, has no power or what? Thanks Brad.

With the input line disconnected at the fuel pump, and air pressure(not a lot) added to the filler neck on the tank, you should see fuel flowing out of the fuel pump end of the fuel line. If not, your problem is between the tank and the end of the fuel line.

That may be true with a bottom feed tank but not sure with a TF style pick up tube. If you have done that, I yield. There seems to be no way it can be blocked with all new system unless a rubber hose is kinked. The flow test needs to be done ASAP and I would like to know how the truck runs. This truck may have a vented cap issue. He says he "clears" it by back blowing. That means an obstruction is going out into the sock, then back in? I don't buy that. Also you can blow the sock off that way.

bartamos it will still work on a TF truck with a top feed, or he can suck on the fuel pump end to get the gas flowing like we did when we were kids stealing gas.

Good to know. Thanks Brian. We will see what Brad reports about flow test.

OK- Thank you all for trying to help out- I have not done a flow test, per say, and I'll restate some things after the follow-on questions, and try to clarify the issue:

-No filter in the system anywhere, yet.
-Everything concerning fuel capping, filling, storage, supply, sending, & pumping is brand new.
-Motor won't start (for a while) is the problem, or without some coercion

Initial Problem on run-in--8/30/2015

I'm not being a smart ___ here, but the motor would not start until it got fuel; hence the investigation (post this "initial problem" on the initial engine run-in that I am describing right now in this paragraph). It took seven or eight five to ten second-long (estimated) starting attempts for the engine's carburetor to be supplied enough fuel to continue running past the fuel amount squirted into the bowl. The engine fired off, we got RPM to 2K, (no stumbles, bumps, hesitation, etc) and it ran fine for the initial run-in period. It "fired off, and it ran fine" quick enough during this initial run-in procedure that no fuel supply investigation was required; other than listed below in "Initial diagnosis/observations--8/30/2015"

Initial diagnosis/observations--8/30/2015

At about the fourth no-start:
-All other no-start variables were eliminated as they checked out- timing, battery, coil wires, etc.
-Fuel in the tank? Yes; visually verified 5-6 gallons 100% gasoline in the new fuel tank; this amount of fuel was also missing from the portable gas tank I poured it from 30 minutes prior. The fuel gauge wiring is not connected at this point- (typing this I'm having a "hmmmm?" moment)
-All lines connected & tight? Yes; one line, a flexible fuel line coming out of the cab floor had minimal fuel seepage, so it was tightened. No crimps in fuel lines were observed from the sending unit to the fuel pump; nor from the fuel pump to the carburetor.
-Fuel getting to Carb? Eventually- yes; we disconnected the carb fuel inlet & finally got some fuel to come out it a bottle. I would estimate the amount of fuel that came out was appropriate for the 'new' 4149 fuel pump's pressure rating.

At this point on 8/30/2015 the engine started, ran fine for the run-in, and no additional problems were noted concerning fuel supply issues.
------
Continued Problem, post run-in--8/30/2015

(After the break in procedure, I connected some new gauges, and wanted to run the engine again to verify some numbers. The engine eventually ran this time, as well, but now we're getting into starting times required that are borderline 'burn up a starter' lengths of time when looked at as a whole. The turning-over times for the starter were no longer in duration than before, but collectively it was adding up)

45 minutes to 1 hour after the above "Initial Problem on run-in--8/30/2015":
Same 'no fuel' issue

Continued Problem, post run-in--8/30/2015-- Observations

-No fuel to carb observed with disconnected line from carb inlet (when bumping starter)
-No fuel at fuel pump inlet (from gas tank, straight line, no filter) when I disconnected the fuel line. As in, fuel did not come out at all; the way you would expect it to do after running for 20 minutes within the hour. Re-verified by sound that fuel was still in the tank.
-At this point I removed the fuel pump inlet line & blew a small amount of air down the fuel line with a bicycle pump. I heard a little burp noise in the tank, and re-connected the line to the disconnected fuel pump (off of the motor). With only the intake line attached to the fuel pump, I actuated the lever and gas squirted out the pump's outlet very forceful. I didn't know this was not an adequate test, but I'm learning. EDIT- the fuel that came out might have just been already in the pump, I guess
-Connected everything back to the engine and it ran fine, again.

BUT... there is a problem somewhere here- keep asking questions. I'm interested in the 'vent' issue described. Being new tank, filler neck, et cetera, some kind of a vacuum(?) problem in the system would make sense. I will do the flow test as soon as I can; how much air needs to be forced?

Thanks
Brad
I'm looking for the video of this particular start & I'll post it.

This was my thought in blowing a little bike pump air down the line. I realize the danger with the sock coming off now- thanks for posting that bartamos.
Brad

I have no clue, Joe. The problem would make sense, though. It's an Airtex 4149, I'm fairly positive.
Thanks
Brad

There is great confusion amongst us which I have tried to correct. Let me restate. There is no benefit to disconnecting the pump inlet. The inlet is the side of the pump from the tank. If I read you disconnected the inlet and bumped the starter, you would not get gas coming out the pipe because the pump is, at that point, disconnected! Maybe I read it wrong. Anyway here is what a flow test is: Install pump on motor, CONNECT pump inlet line from tank. DISCONNECT line at carb.(carb inlet) Put disconnected carb line end into a quart container. DISCONNECT center tap on distributor so motor does not start and no sparks to cause fire. Then crank starter and watch fuel being pumped into the container as if it was being pumped into carb. You should see a fairly good pulsating stream of fuel and start to fill up container pretty fast. This test tells you that pump is good and everything, all the way back to fuel pick up tube, is good. Be SURE you have fuel in tank. All effort is being wasted until this is done. If it does not squirt very well, take off gas cap and try again. If it does squirt well, proceed to think bad carb or electrics. If you must blow air AFTER the flow test, disconnect line at sender outlet and disconnect line at pump inlet and blow to be sure line is clear, real clear. Also disconnect line at carb and at pump outlet and check that line for clear. No need to blow into tank forward or backwards. If we ever get to the point that we think something is clogged in tank we will proceed to suck from a gas can. NOT YET! You will not be able to sleep until you do a proper flow test. Be sure no rubber line is collapsing, as in: you used old rubber or not fuel line rubber.

This sounds like a flow test has been done. If in fact this is a flow test and it tested good and as long as you realize it should pump right away and pretty forcefully, NOT tiny squirts or dribble, then you have a carburetor problem (if I trust your electrical check.) Best check is at plug gap. If it does not squirt properly then a different proceedure is next. I understand it is a new pump. A TF tank is vented to the cap and cap needs to be a vented type cap. If fuel flows in a flow test, you don't have any problems with fuel delivery to carb. Now I'm being a smart arse.

This makes no sense.

You are correct, no filter is necessary and no gauge is necessary at this time.

I disconnected the fuel pump inlet line just to see if any fuel was there. There was none. I did not think that every time you shut an engine off the gas tank would reclaim all of its fuel by sucking it back from the lines. Does this usually occur? That's just the point I was trying to make. I have not bumped the starter with this line disconnected because that just wouldn't make sense, but I understand where the confusion came from - my apologies.

I disconnected the carb inlet line, downstream from the fuel pump, from the side of the carburetor, then bumped the starter. No fuel came out of this line (the one that would usually supply fuel to the carb).

So, I did do a flow test as stated here:


BUT, AFTER no fuel was present, and AFTER blowing air down the line with the bicycle pump, and reconnecting everything, there obviously was fuel to the carb because the engine ran.

Later tonight, I will re-do the flow test as stated above, and just start the process over.

Man I think we are typing over each other or something.


Look, tonight I will start from scratch:
unhook tower center wire,
disconnect fuel line at carb and put it in a container,
and I'll report back.

How long is 'too long' for fuel to make it from the tank to the carb?

Brad

8 seconds is too long, but who knows? One more test is a good idea. If it does not flow, try with cap off. If still no flow install rubber test hose from pump inlet down into a gas can. If still no flow at pump outlet, get another pump. (be sure pump arm is on cam)
If on testing it does flow, then reconnect line to carb, crank some to fill carb, then look down into carb with flashlight and see it squirt when throttle is rotated. No squirt? no start? Pour some gas in there and crank. (with dizzy hooked up). Should absolutely start if electrics are good. If it starts then you have pretty much proven it's the carb. Hang in there Bro.

Logic (which is only a starting point) says if everything is new, and working like new, up to carb, it's the carb or electrics. Timing, plugs, wires, dizzy, coil........
If you pour/squirt gas in there and it fires up real quick, that's good news. Be careful, too much gas will flood it.

I am using that Airtex pump, but the first one I bought was DOA.

Someone posted the Carter number - M2118
http://www.summitracing.com/parts/crt-m2118/overview/make/chevrolet
It is readily available from many vendors.

I'll use that in the future.

The orientation of inlet/outlet changed over the years.

Good to know on several points there, thanks.

Here's a wrinkle... All of the above, engine running, fuel not making it, et cetera, was with a borrowed "known good carburetor" that is no longer in the picture. I borrowed it for the run-in, and it did its job. I had exactly what was needed to start, monitor, & shut off the engine hooked up. It just took me a week to rebuild my carb & connect everything such as linkages, controls, cables, so I'm just now getting to the fuel problem.

I will focus on another flow test, first, then we can worry about my rebuilt carburetor coming into the equation.

Edit- I'm picking up another new fuel pump, anyway, just so I have it if needed.

Brad

Something I just thought of....If there's a small leak somewhere that isn't getting your attention, is there a chance that the gas is leaking out in small enough quantities from between the tank and fuel pump that you're basically having to prime the system every time it sits long enough? I didn't read all the postings above and am happy to sit on the sidelines if this has already been checked.

No fuel is leaking, but I did find a loose fitting that I tightened prior to first start.

Just a dumb grunt here, so I need the reminding either way.

Brad

Brad: Excellent. You are not a d____ g____. Glad to see full disclosure about carb. It's too hard to figure out, by reading everything, if/when rebuild carb came in. Also "known good carb" just used on a motor? or sitting on a shelf for months? If you put the rebuilt carb on and it starts and runs. Game over. I'm enjoying the investigation. I learn allot for when it happens to me.

You don't need a lot of air pressure to pressurize the tank to get fuel flow out of the fuel pump feed line. But you need volume and a bicycle pump isn't going to cut it. You need an air compressor.

The "known good carb" was driven to my house on a '62 truck with a 235 engine, removed, and hooked up to my intake. I'd say that's as "known good" as I could hope for on an engine run-in. This carburetor is currently back on the much younger truck; I'm sure doing just fine.
---------------
My flow test (30 minutes ago):

Surprising results tonight with the status quo of my engine, fuel pump, et al. I did not change a thing, and just to try it, I turned the engine over and got fuel at the carb, in a bottle. Fairly quick & that is what was so surprising to me... Not much fuel at all, however. Maybe one ounce. Again, I verified fuel was in the tank.

I will post the videos in a little while. I went ahead and pretended there were never any fuel issues & connected the fuel line to the Carter YF 2100s carb I just rebuilt- it almost acted like it was going to run. I forgot to try the test with the gas cap off & I'm just remembering that.

Stick around...

Brad

put 5 more gallons of gas in it.

That was on my mind & I will be doing that next. There may be seven (7) gallons in the tank now.

Start attempt mentioned earlier with unknown fresh rebuilt carb (set per Carter manual)

Brad

Fuel test: Quick flow but not much? How long did you crank to get "not much"? What does not much mean? Weak squirts? Not steady pulsating squirts? Dribble? Did not try a long time? An ounce in what time period? Once it starts squirting it should keep going, like a pump squirt every second or so. Keep cranking non stop. But you have to see it yourself while someone else is cranking. This is not a "bump the starter" test. It's a whole hog 10-12 full seconds crank.
Anyway, use the choke and see if it starts. Suck from gas can. No start? Then return pump for another. No start? Reset float level and float drop carefully....and check accelerator pump. No start after that? Flow test replacement pump.
Have you ever rebuilt a carb before?
Pretty sure it's not the cap. Don't dwell on what I said about cap.
AFTER another pump is installed and won't start, it would be nice to borrow the carb again. If it does not start after that, crash it into the river and collect the insurance.
Hope you did not blow air into the pump, you will damage it.

Next step-

I can install the new fuel pump I have (edit-same 4149 model; I purchased new one this morning), but I may return it and go with the Carter model linked above by Tim. I only had 15 minutes last night to do any testing, which verified (in my understanding) that I need a new fuel pump. Since I now know the colloquialism "flow test" is the same thing I have done well over one-hundred (100) times previously, on various engines, the pump installed does not produce acceptable flow. My fuel pump's lack of "acceptable flow" determination is based on the following (and please correct me if I'm wrong):

Fuel test: Quick flow but not much? Correct
How long did you crank to get "not much"? 15 seconds
What does not much mean? In this context "not much" is equal to or less than one US ounce of fluid, or 30 mL. I think I said that, but I understand why you axed me. I will take care with my use of quantifiers from now on
Weak squirts? Correct
Not steady pulsating squirts? Correct, they were not
Dribble? Correct- after the initial one ounce, and only a tinkle dribble, QTY- 1
Did not try a long time? Quantify "long time"
An ounce in what time period? 15 Seconds
Once it starts squirting it should keep going...pump squirt every second or so. This did not happen.
Keep cranking non stop. But you have to see it yourself while someone else is cranking. I saw this for myself, peering between the hood & cowl opening. I also watched it on video.
This is not a "bump the starter" test. It's a whole hog 10-12 full seconds crank. My flow test met this criteria.

I only attempted the start (in the video I linked above) because in the time allotted I could connect the fuel fitting to the carb (1) & re-connect the coil wire (1); I did not have time to do a fuel pump swap (2 screws, 2 line fittings + the wire(1) & carb line (1). Other relevant answers:

Have you ever rebuilt a carb before? Yes-log splitters, tractors, generators, Rochesters, Carters... this is the first Carter YF 2100s, though
Don't dwell on what I said about cap. I'm not.
Hope you did not blow air into the pump, you will damage it. I did not blow air into the pump.

Let me know if anything stands out from my above answers leading anyone to believe this is not a fuel pump issue.

Thanks-
Brad

Sounds like it is fuel pump but we will see. It's disappointing that there are "new" parts that do not operate. Sad, but true. It's hard to diagnose any problem when all new parts are present.
I just don't want to believe one of them is bad. The probabilities are it's something else. Waiting for your results.
The gas pour did point to pump (or carb.)...or no gas in tank

There is gas in the tank. I also got some more 100% gasoline (QTY 4.54 gallons) to pour in as advised above. $10.00 worth @ $2.20 gallon for ethanol free is the only reason I know the quantity.

Adding 4 more gallons to the tank should have it right at 3/4 full. Or, 1/4 empty. I will check back in this afternoon; just for the sake of it I will add the extra fuel and flow test again with the same pump that is already installed. I'm already set up to do that anyway & I'd rather exhaust all variables before I install a $40+ fuel pump.

You mean when I tried to start the engine and poured gas down the carb?

Brad

Yes, I meant the pour down carb. Good idea to be sure of a baseline pump flow test...one more time. You think like I do.
1. Gas in tank
2. No kinks or collapsed hose
3. No filters
4. The next new pump has to work, will work. Be sure arm of pump is positioned correctly. Pump should be hard to put in or it's not right.

From one to another

OK; here's a video update of the fuel issue when I added the four (4) gallons of fuel to the tank. I also bent a new line from the pump to the carb. I also videoed the fuel lines just to verify to myself they were still there. Flow test with more fuel. I think it's 3 minutes long.

I did two more tries, longer cranking than these on video (one we counted out loud to ten) and still no fuel to carb. So, in total, 30 seconds of sequential cranking yielded 0 fuel to the bottle/carburetor. I'm installing the new fuel pump right now.

Brad

New fuel pump success ... finally. My previous post - I forgot to submit about an our ago. I ain't a fuel-pump-changin' speed demon or anything.

Watch the video; This was about the tenth try to get fuel to the carb/bottle at the same length of cranking---with the new pump. Seems like a long time (?) for fuel to get there, even with a new fuel pump.... I had already removed the sending unit to take a picture to prove that there was gas in the tank... (and to check it out for any odd obstruction). Fuel sending unit removal pictures. If anyone is curious, and looks at the pictures, I used 91% alcohol to clean out the water bottle. It left a residue inside the bottle causing the gas to become cloudy when it pumped into it.

I'd never tested that reaction before, but now we know.

Of course, in the video I just posted, I had re-installed the gas tank sending unit. Thanks for the help, gents. Let's fire it up tomorrow.

Brad

It's tomorrow now. Wake up your son and you two get out there.

Wilco.

Brad

Red leader to blue leader, come in blue leader. Many parsecs have passed. Running is the truck yet?

My truck just acted like Forest Gump & said, "I was runn-nang!"

I'll have to do some adjustments, which I will ask about, but it fired off running with my carburetor - on the first attempt...

Once I upload the video, I will post it for some advice. I'm hesitant to share what I think, because the lack of an exhaust gasket (waiting to get money for full pipes) & the flange's loose connection has me unsure what I'm hearing.

I slow the owner down a lot, but I'm doing my best.

Brad

Here's the video.

Brad