Engine Problems

[medium8080]

I have a 72 Scout with a 304 running a howell fuel injection setup. I haven't had a single problem with it for over 8 years.

During the day I was at a stop light and started to go, but my truck stalled, when I let out the clutch. It took a few tries for it to start back up which was odd, because my truck always fires up instantly.

Later that night I was at another stop light and the same thing happened, but it wouldn't fire back up. I had to push it off the road and wait for aaa to come tow me home.

I waited about 45 minutes for the tow truck and tried to keep starting my truck every 10 minutes or so, while I was waiting, but it never started up so I towed it home.

When I got home and rolled it off the tow truck I tried to start it again to drive it into the garage and it started up, but it was making an exhaust leak type of sound.

I have no idea what could be causing it to make the sound, and I really hope I don't have a major engine problem.

So...

What could be wrong with my engine?

Could it be a problem with a valve, timing gear, or bearing?

Thanks

 

[Michael Mayben]

This issue is going to take much more in the way of in-depth diagnostics than just a "what do I do?" request!

If you installed the howell system, you should understand all the diagnostic process that was part of the install, such as checking the basics of fuel supply, spark production, etc.

Since the vehicle started after sitting for a period, I'd certainly suspect that an electrical/electronic component has decided to become intermittent. But you haven't told us what ignition system is being used and what type of efi interface is being used so we have nowhere to go with that at this point.

Was the efi harness interfaced with the oem sii wiring? If so, have the bulkhead connectors been upgraded/exchanged?

When the engine stalled, were all other electrical loads operational? What's the charging system diagnostics tell you, is the alternator and battery system functional and charging at the appropriate rate vs. Engine rpm?

Will the fuel pump energize when fuel pressure is released?

In order to diagnose the noise, you will first need to have the engine starting/running in a somewhat reliable fashion. Then use a piece of vacuum tubing in an ear as a stethoscope and attempt to pinpoint the noise, it May not be related at all to the stalling issue.

 

[medium8080]

I'm running a d.u.I. Distributor and it is the TBI efi kit

I originally suspected it to be a fuel or electrical problem, but when I heard the exhaust leak type of noise that it was making, I thought it was a valve/timing sort of problem.

I had anything Scout install the efi kit, so I actually don't know the details of the wiring, but the stock bulkeheads are still there.

Everything electrically, headlights/stereo, was working fine when it stalled.

I haven't tried to start it again to diagnose anything because I wasn't sure if I could cause any damage to the engine.

Do I need to worry about causing damage to the engine, or is the damage already done, if there is any at all?

 

[Michael Mayben]

I'm running a d.u.I. Distributor and it is the TBI efi kit

I originally suspected it to be a fuel or electrical problem, but when I heard the exhaust leak type of noise that it was making, I thought it was a valve/timing sort of problem.

I had anything Scout install the efi kit, so I actually don't know the details of the wiring, but the stock bulkeheads are still there.

Everything electrically, headlights/stereo, was working fine when it stalled.

I haven't tried to start it again to diagnose anything because I wasn't sure if I could cause any damage to the engine.

Do I need to worry about causing damage to the engine, or is the damage already done, if there is any at all?

So if you have a dui distributor, it most likely is not interfaced with the efi system. All that needs to be addressed with bill in our efi sub-forum, I'm not the person to help ya with that aspect. But I do know that if your dui is running only two wires into it's connector (switched b+ and a tach signal), then it's not talking to the ECM unless it's been jumpered internally and the module moved out of the distributor and placed in another location.

Since you did not loose the rest of the electrics when this happened, then the bulkhead connector can most likely be ruled out. But I'd still pull it out and verify it's condition internally regarding the contacts. I can't believe it's still present and you haven't had issues with that aspect! But then, I have no idea how the efi harness was interfaced with the oem electrics, we're gonna need good pics of the wiring harness routing and the interface!

If the distributor is running the "module" (amplifier) inside the dui as in an oem GM application, then loosing fire on an intermittent basis and then it "corrects" itself after sitting for a while, is nearly always caused by a faulty module, those take a dump when hot and then just quit. This failure is extremely common with any form of dui-type distributor, even the high end units from msd, et al.

That hei module (not the coil) must be bedded onto it's mount using a heat-conductive dielectric compound, if it's installed dry, it will overheat and fail in a short while. All forms of electronic ignition that use amplifiers of some sort (delco hei, Holley gold box, prestolite 4000 series, chrysler electronic, Ford duraspark, etc.) will fail when subjected to an elevated temperature.

If it's running an externally-mounted module (probably a seven pin unit), then the same thing can occurs, the module simply fails. That is why when the engine stalls on one of these efi conversions, we gotta verify spark at the plug first to be able to determine if the issue is fuel-related, ignition-related, or ECM/sensor-related. Any of those issues would also show up if a scan tool is connected and the failure/glitch has set a code.

If this were in my shop, I'd run it (as long as it will) and pinpoint the source of the "new" noise. Most likely area is the rocker shaft assembly on one or both sides, you can see we address this lifter/lubrication issue constantly around here.

While you are looking for the noise, it's likely it will stall again. That is when we need to look for root cause of that issue,...such as "no spark at the plugs", no fuel pressure, etc.

Another very common cause of noise that just comes on all of a sudden is as you mentioned an exhaust leak at the exhaust pipe/manifold junction. When an engine looses it's ignition (as you May have), most of the time a backfire will occur which you May not have noticed. That in turn can blow out a weakened exhaust donut or gasket. So use that redneck stethoscope I mentioned to probe around the manifold connections also.