The Stovebolt Site Forums The Shop Area Engine Shop Fuel pump questions

1. I think (but my wife says not very good) that fuel pumps on a 52 Chevy truck and my '52 GMC truck will interchange. Anyone have an opinion?

2. I recently came across two fuel pumps among a bunch of GMC 228 parts. One has a rebuilder's tag "531" and no other markings. An online picture of an Airtex 531 looks very similar. The other is a Carter MO-735. I'm too lazy (it is 102.4 degrees outside right now and my garage does not have A/C) to pull the pump off of my truck to see if either will fit. Both have seen better days. I'm considering having one rebuilt for use as a spare.
2a. Who would you send the pump to?
2b. Which pump would you send?

I might be inclined to rebuild it myself, Bill. Then & Now has the best rebuilding kits and I'm certain they can tell you everything you need to know about which pump will be the best to rebuild. For what it may be worth, I think the 52 Chevy and 52 GMC will interchange. Yes, very hot.

I can help with 2a. but not a clue on the other questions.

Then and Now Automotive can rebuild either pump for you, or sell you a rebuild kit so you could do it yourself. They may be able to help you ID which pump to use.

I'm gonna guess that either pump would work fine on your truck.
Any stamped numbers around the screws holding it together? That's how I ID'd mine to get a rebuild kit from Then and Now.

[on edit] Looks like Jon types faster than me. Hot here too, yesterday. Got all the way up to 70F.

Then and Now rebuilt my glass bowl pump over a year ago after two new ones failed when I opened the cardboard box they came in.

They'll sell you a kit but for an extra $50 , they'll do it for you. New filter, pins, diaphragm, gaskets, etc.

I'm not afraid to do it myself. I just didn't realize kits were available. I'll contact Then&Now and ask their opinion on which pump to rebuild. Thanks guys.

There was a metal can AC filter on the no-name pump. I opened it up and found no filter element inside.

The truck has electric wipers, so I don't need a dual pump. But the engine came to me with vacuum wipers and a dual pump. I changed to electric wipers (work great), but left the working well dual pump. Just plumbed the input to the output on the wiper chamber.

If you can find a number like the attached pic on your pump, that will give them the info for the proper repair kit. The pump in the pic is one with a glass bowl filter on top. The number on it matched up with their FPA-146 kit

I’m not trying to hijack the thread, but I would like to know what the difference is between 216 and 235 fuel pumps. I have a glass bowl one that I would like to rebuild if it’s for the 216. The only numbers I have found are 1523093 on the arm and 40121 on the side of the flange where it mounts to the engine. It has been rebuilt in the past as it is stamped “Rebuilt For AC”. Thanks guys for your help. Now back to your previously scheduled program.

Call Then and Now and ask for Tom. He's forgotten more about fuel pumps than most folks will ever know. Good people.

Bill, I can tell you from my research and experience of all the aftermarket parts the most likely one to be junk and fail is a mechanical fuel pump. Regardless of the brand. As everyone has indicated, rebuilding an original is your best option. I am on my 3rd fuel pump with a grand total of less than 10 hours on all 3 of them combined. The last one seems to be doing okay and the only reason I put it on is because the 2nd one that failed was a Carter and had a one year warranty. They gave me a replacement at no cost or I would have gone the Then and Now route. If this one fails, they are my next stop. FYI - Carter use to be a quality name in auto parts. I found out my Carter fuel pump was made in China.

Otto, your pictures show the fuel pump with the glass bowl pointing up. I thought they were supposed to be point down to collect any debris coming through the line? My fuel pump only work with the bowl down.

I am having the same problems with after market replacements as well. My Airtex #4149 (made in Illinois 20 years ago) was leaking fuel. I ordered a replacement from a specialty vendor (same model but made in Mexico?) and it quit on me about 10 miles from home. Ordered another from NAPA and the truck is running but there is not a continuous flow, it seems to come in spurts, sometimes leaving the filter before the carb empty. Gonna have to look at a rebuild kit from Then and Now

You might be fine. Do some poking around the site for a procedure on fuel pump test.

By some mystery of the universe, a clear filter on a fully functional pump will look and behave exactly as you describe. At least some of the time.

I’d definitely test before assuming the pump is bad.

Contrary to popular belief, the glass bowl is not a sediment bowl. It is simply a cover for the filter on the pump. GM never referred to it as a sediment bowl but calls it a cover in literature.

It mounts on the truck with the glass cover on top. If you have a 216 with the same kind of fuel pump I have, it will only mount as you see in my photo.

The same is true fro the glass bowl AC filters found on many GM cars in the '50s and '60s. They are not sediment bowls regardless of how they are oriented on the engine.

Some GM brands mount them with the glass bowl on the bottom leading many to believe it acts as a sediment bowl. Cadillac mounted the filter with the glass bowl on top.

The turbulence created by the fuel pumps inside both types of filter bowls makes it impossible to collect sediment. That's what the filter element is for.

My filter was a Re-man unit from Airtex as well. It may have started life as an original GM unit. Either way, it was from a long time ago when authentic OEM parts were rebuilt in the USA. Since cores have become scarce, bad copies are being made new but they're junk from the get go.

Then and Now did a great job on it.

Bluetruck,

I will confirm what JW51 says about the action of the fuel inside the glass bowl. All of the vehicles I own with glass bowl filters and the AD fuel pump/filter combo behave the same way. Sometimes it looks like a continuous flow, sometimes its spurting, sometimes it looks empty yet the engines keep running smoothly.

It's the nature of the beast and not an indication of trouble.

JW51, I will do some looking for the fuel pump test. Cape? Small world isn’t it!

OTTO, my filter is the NAPA plastic aftermarket one. Seems strange for a mechanical pump only pumping sporadically and not activated by the cam lobe. Did you send yours to Then and Now to rebuild? I tried calling them, got a message they are short handed and to call back or send an email. How much and what is the turnaround on a rebuild?

Jim Carter shows USA made fuel pumps in their catalog, if that helps.

Sparky,
Thanks, they were out of stock a week or three ago when I initially started my search. Good to know!

This is the model I am replacing. Original on left with the first replacement on the right. That one quit on me 10 miles from home. Sorry to jack the the thread Bill Hanlon

The kit from them to rebuild it myself was $52. They rebuilt it for $115. I thought paying them $63 to do it was a bargain. Turnaround time was a week. It took a couple days to get there, a couple days to get back, and I guess they had it no more than 3 or 4 days in their shop.

Welcome to the club, Blue.

Gold one lasted a couple hundred miles or so. Silver one wouldn't pump a drop straight out of the box.

You might be wise to proactively rebuild a pump with good parts, rather than depend on a new one with a high chance of failure᠁.but you have to basically ignore whatever is going on inside your clear filter.

Your current pump might very well be working fine. If it’s running fine, that’s one piece of evidence. Further confirmation would come from testing pressure and volume.

I got myself all spun up about the same weirdness inside my clear filter a few years back. I did receive some explanations, which didn’t make much sense to me. But I finally learned to ignore it as long as the engine was happy.

Nice to see Mr. Hanlon's problem is fixed.

Back in the mid-90s I gave up completely on the mechanical fuel pumps as a couple had left me stranded and highly agitato. I went to a low psi electric pump. Then later I decided I wanted a spin-on oil filter and ran the plumbing out of the way of the crankshaft and out through the hole where the fuel pump had originally been...all having been done with copper pipe, removeable fittings and aftermarket oil filter appliance so it could be reversed in case anyone later wanted a mechanical pump. I made a block-off plate of brass so the in/out lines could be soldered to it.

The electric fuel pump I used worked fine for over 20 years and I replaced it with the exact same one just because it wasn't expensive and a new one seemed prudent.

You can sort of see what I did in the images below.

Jon G:

“The electric fuel pump I used worked fine for over 20 years and I replaced it with the exact same one just because it wasn't expensive and a new one seemed prudent.”

Do you have a part number for this electric fuel pump?
Thanks, Dave

Dave it is Autobest F4027. The output pressure on mine is 2.5 to 3.2 psi. You can see it on Amazon (for one source). Autobest from what I've read began in China around 1994 and since 2007 has been in the USA.

Curious᠁ did you wire it through some sort of safety switch?

(I think an oil pressure switch is one way people do this).

I'm going rogue on it until I think of something that makes sense to me.

Oil pressure switch is the most common but I don't have one of those as I use a mechanical oil pressure gauge. And these only work if your engine dies in a wreck...which generally speaking does happen but may not. In 1971 a friend and I came up on a wreck involving a Fiat Spider...driver was dead and engine was still running. Running very fast, in fact. The car had been hit with a glancing head-on blow that struck right behind the driver's side wheel and had been either knocked out of gear somehow or the driver struck the shift lever in the impact. We later wondered if it could have been hit hard enough to just separate the driveshaft from the transmission. Aside from the area in front of the point of impact it was a horrific mess.

A mercury switch is what I've seen some folks use (if you flip the vehicle over it breaks contact in the fuel pump circuit...but it seems to me if you flip over and over you can presumably land right side up and then you could catch fire or explode anyway. Seemed to me a scheme Ford Pinto engineers might have thought made sense.

And there are inertia switches. Another "better" Ford idea which hasn't worked nearly as well as the person/people who came up with it probably hoped it would. From what I've read they fail fairly frequently and can be tripped by anything from a pothole to a speed bump to driving on a flat tire. With the smooth AD suspension I can see these things being tripped by driving down a gravel road. So, I don't know. I should do something but I haven't decided what.

Ya, there's a secret fuel pump "reset" switch in the F-150 glove boxes to re-activate it after it shuts off for whatever reason. In all honesty it doesn't happen all that much and has never happened to me or anyone I know. It does happen often enough though, to be "a thing" .

The “what to do” about a safety cutoff is what has kept me from already installing the pump you recommend.

I like making little reliability improvements, without introducing new failure points, or some gadget that would be hard to source if a guy was away from home and had to find something off the shelf.

Your electric pump is nice in that it doesn’t introduce the need for an external regulator (new failure point). It’s also cheap enough that you could easily throw a spare in the glovebox.

I like the simplicity of the mechanical pump. But I think the failures are more common than successes with the modern ones. Even if mine is working great now, where does my next replacement come from? (The Then and Now rebuild kits are probably the best option).

Inertia switches look goofy to me, even though I know nothing about the actual failure rate. The oil pressure switch is probably better, but those are certainly just as offshore and sketchy as any other part these days.

We have various kinds of “dead man switches” in my workplace that are safety interlocks requiring a person to be standing in a certain place, touching a certain button to ensure hands are not in equipment, etc. Something along those lines might be the ticket. Worthy of more consideration.

Jon G: thanks for that fuel pump PN and pressure specs.
Good info, and I second the idea of running the circuit in series with the oil pressure switch. Regards, Dave

What about running both, a mercury switch and an oil pressure switch?

Might as well throw a manual toggle switch into the mix as well. Have three ways to shut off the fuel and three more sources of failure.

When was the last time you were in a rollover crash? Statistically speaking it's not likely to happen.

Figure out which method you like best and install it.

Not a bad scheme, Phil. Actually the oil pressure switch would probably be fine for most AD applications. Just me and my tendency to want as few loose ends as possible on something like this. Of all the schemes out there I think the inertia switch is definitely the one least likely to work with the AD truck given its harsh suspension and all. I can see having to wire the re-set button as the horn pad, you know. Either that or having one that requires the truck be hit by a meteor or driving by a grain elevator when it explodes in order to trip it.

Jon G, did you wire that pump through a relay or just straight up?

Straight up to the on terminal of the ignition switch. It uses very little juice so it seemed logical to do that. The HEI coil because of the high amp startup draw (and the possibility it could damage the ignition switch even though the time period is short) and the two fans are run through Bosch style relays, though. Think I used 60 amp relays for the fans and I may have used a 30 amp for the HEI coil.

An update on my fuel pump(s). The second one has been working as normal with some short drives on the backroads. I have tried to reach Then and Now a couple times by phone and sent a couple emails but no answer. They seem to be real busy and short handed. I’m tempted to just send my old USA made Airtex to them for a rebuild and have it ready and waiting when this one bites the dust.

The one they rebuilt for me was an Airtex. I am extremely happy with it/them.

Yes, I'd send it with a note and a full description of the engine/vehicle

John,
I'm having to put in a electric fuel pump and was wondering if I can put it in line with the mechanical one or if the mechanical one should be bypassed?
James

If you are going to use the electric pump full time you should bypass the mech. pump. If the diaphragm should leak it will flood the crankcase with gas.
If you use the elec. pump as a primer for starting you can run it through the mech. pump.

George

Update on my fuel pump.

I decided to buy a NOS AC 4149 and a rebuild kit from Then and Now to replace the foreign made 4149 currently on the truck. It took a while to get the rebuild kit due to their staffing issues but finally got it. I decided to just replace the diaphragm and pulsator and leave the valves alone and give it a shot. Working better and seems to pump a more consistent stream of fuel, no hesitation at all. Only put a few miles on it so we will see.

Some pictures attached. $3.00 was written pump box! I did not pay that LOL.

You may want to go back and replace those valves. I've discovered, especially or in particular with the Airtex fuel pumps that it's the valves that fail. Sometimes they aren't staked properly and actually come out of their seat and hop around inside the fuel pump