The Stovebolt Site Forums The Shop Area Engine Shop 228 GMC not running ... Help

WE installed a 228 that run good for about 8 miles. Then it seemed to lose power. Eventually it backfired a few times an stopped running all together. All 6 plugs have spark and I sprayed a little starting fluid down the carb and nothing. When I crank the motor it will puff a little but will not start. I was told that the cam gear is nylon and might have broke a tooth. I removed the timing cover to find an aluminum gear that looks to be in fine condition. The only other thing I noted is there was an exhaust leak that was pretty bad by the time it stoped running. Would this cause the engine to not run at all due to lack of backpressure? Any advice would be appreciated.

Thanks.
Trey

Did the distributor loosen causing the ignition timing to change?

Trey,

That's quite a chore to pull the timing cover. It sure sounds like lack of fuel, but I would go through a tune up routine and you will probably find the culprit.

You indicated the plugs showed fire, but I would set the points accurately, and like Grigg notes, check the timing.

Eight miles is a long way to run while starving for fuel but make sure you have no plugged filters, collapsed hoses or dead bugs caught in the needle and seat.

Another idea might be a coil that is failing as it warms up or a bad condenser. There are no back pressure ramifications on these engines so the exhaust leak would not be a concern.

You said it ran 8 miles and fizzled. Did you get it started again for another 8 mile run or was it a one shot deal?

Stuart

It has not ran again since the origional 8 miles. I have also changed it to an electronic ignition. The cap and rotor I replaced less than a year ago. I also took the coil from the truck and installed it on another car and it ran fine. Also I had been driving the truck on a regular basis for about the last year +.

Thanks for the replys.

So is the ignition timing set right?

Grigg

If the exhaust leak is between the head and manifold there may be a vacuum leak there too. I don't see how it could be so big as to not let fuel get to any cylinders. Check that by spraying starting fluid between head and intake ports while someone cranks the engine. Be careful of back fires! I'm not absolutely sure of this but I think there are two types of aluminum cam gears. One is all aluminum and one has a steel core. I have heard of the gear shifting on the core thus changing cam timing. First I would check ignition timing and ALL wires, coil condenser etc. If no go I'd squirt fuel directly into the cylinders. If no go I'd pull the valve cover and check rocker position relative to #1 piston. Pretty much as you would when adjusting valve lash. Good luck, let us know what you find.

Treyz,

You changed it (ignition) after the incident in an attempt to remedy the problem, is that right, or was it electronic during it's episode?

I think something is being overlooked here. If it has spark, which you say it does, then squirting starting fluid into it should make it pop. I would try a little gasoline myself as sometimes it acts differently than the starting fluid.

Because of the way it died, I wouldn't spend much time on major mechanical maladies like a broken timing gear or snapped crankshaft. The electronic ignition would be a real prime suspect, but my guess is this was installed after the fact.

Don't give up, you're smarter than the truck!

Stuart

the electronic ignition has been installed for about 8000 miles on the other engine then transfered to the new motor that ran about 8 miles then stopped.

Treyz,

I would do whatever it took to prove that electronic ignition was 100% operational. Your glitch sounds like it might be caused by this item. The generic 'failed module' comes to mind and I have seen posts here before where this units would run for awhile, fail and repeat the process over and over until replaced.

You stated you had spark, but I'm not sure that covers the health of this thing. What kind of voltage do you have supplying it...full voltage or some type of reduced voltage. What does the unit require.

If it has a coil, maybe it's some type of a Pertronix or such. These units have been know to have problems (the ignition module, not the coil).

This may be a wild goose chase, but at least it gives you a direction.

Stuart

I still think ignition timing is a likely suspect, check it, it won't cost you anything to fix..
Always start with the simple and cheap fixes when trouble shooting.

If you want to check for the valve timing to see if it is way out of time, position the #1 cylinder at TDC compression, then turn the engine a little one way and the the other while watching the rocker arms on #6 cylinder. They should alternate, exhaust closes, and intake opens with not much of a turn either way from TDC.

Might also help us if you can describe how it died, what did it say to you as life slipped away?

Grigg

You need compression, fuel, and spark at the right time to run. Do a compression check, or at least verify that your thumb is popped off the spark plug hole as you crank it. check your fuel system, vacuum leaks, float level, accelerator pump squirting, etc. Check your spark, and it's timing. It's possible that you exhuasr leak could be a head gasket that's blown.

OK, compression test reveals 149 to 162 across all cylinders. I replaced the points back into the distributor and can not get any spark. I have verified that the timing in the motor and distributor are correct. I might have the points wired wrong. I have the wire from the distributor to the negative side of the coil is this correct? I have checked power at the positive side of the coil and it is at 12.5V. The points are gapped at .020

The wire from the points does go to the neg. post. You may have a dead condeser. This can stop spark by grounding it or by burning the points. Also possible the coil is dead. you can check by leaving the positive hooked up, and putting a sparkplug in the high tension lead. Rest the sparkplug against ground. Then take the wire from the negative side and tap it on ground somewhere, with the key on run. This should produce a spark @ the plug. I think you should have a resisiror in the power wire to the coil. My truck has a wire with built in resistor. With out it, you will burn points and condensers like crazy ( maybe every 8 miles?) Your power at the coil should be around 9-9.5 with either a resistor wire or a balast resistor on it. Only eception I know of is when you crank it over, the starter sometimes supplies full volts (12.5) via an extra terminal, to raise the spark level and compensate for the voltage drop of the starter cranking.

Isn't the gmc positive ground? Maybe need to get a positive ground electronic ignition.

Double check your firing order... 1 5 3 6 2 4. Also make sure the distributer hold down is on tight and not allowing the distributer to spin out of timing. It really sounds like that is what happened. It is possible to put the distributer in 180 degrees off.

It does'nt sound like he's been pulling the whole dizzy. Make sure the wire from the coil to the dizzy is not grounded anywhere.

Wait a minute here. GMC is + ground right? On a Chevy the wire from the points to the coil goes to the - side, but Chev's use a - ground. With a + ground, wouldn't that wire go to the + side of the coil?

By the way, a backward-wired coil would heat up and fail in a very short while. I'm thinking you need to change the wires around on the coil and see how far it will run like that.

Waldo,

I asked Treyz the same question on 11/20/07 in a previous post. He never responded, so I assume he has switched over to a negative ground...but I'll assume you know what they say about 'assume'!
Stuart

Check it first, because that would have been obvious when you first took it apart. Just look at the battery cables, if the positive is bolted to ground, there it is!

It has been converted from 6V to a 12V negative ground. I have also ohm tested the point terminal to make sure it is isolated from ground. I picked up a new coil, condinsor, and balast today.I am going to install them this evening and try starting it. I will let you guys know if there is any change.

Thanks.

OK I got fire to the plugs. Now the carb is sneezing. It puffs smoke out the top of the carb. Any ideas?

Thanks.

Treyz,

Good work! It sounds like maybe a timing issue now. Be sure your plug wires are firing in the 153624 order, clockwise around the cap. If nothing else, as you crank it over, move the distributor (loosened) CC or CCW and see if you get the thing to try and take off. Good luck!

Stuart

Also bring cyl. no.1 to top dead center compression, and make sure the rotor is pointing @ the no. tower.

Turn the dizzy a few degrees clockwise (retards the timing) and try again?

PROBLEM FIXED.....

OK Here is what happened. The shaft in the distributor was draging eniough to where it would rotate the distributor out of time. It is draging so much I almost can not turn it by hand. The clamp on the distributor was not tight eniough to keep the distributor from rotating out of time. I installed another distributor that turned easily and of course installed it 180 deg out to add another hour of frustration. Anyway all timing problems solved and the engine is now running again. Your posts kept me focused on timing.

Thanks again for all the info guys.