Hi all,

On my way back from the beach last week, my 85 was just cruising along about 65, then the engine just died- no stumbles, skips, nothing, just died. Pulled over, started right back up, kept going. Drove about 2 more hours died again, but would not start back up. Had it towed to firestone at about 7pm. They looked at it next am, and it fired right up. They let it run all morn and drove it that afternoon no prob. They thought it was the fuel system because the pressure was slightly low, either the filter or pump, and since I had a new pump put on about 2 years ago, had them change the filter.

Drove another 2 hours, dies again at like 9pm. Towed to another shop, same story started right up in the am, idled and drove all day for them no prob. So I picked it up and drove for another hour and it died again.

Had it towed and fuel pump replaced, and it would start up but would not idle and the MAF read low voltage. I've driven with a screwed MAF before, and as long as I wasn't idling, no prob. But now the car drives a minute or two, dies, but starts back up after 1 or 2 tries. The engine stumbles and tries to cut out, but if I give it gas sometimes it goes again or mostly it backfires and dies. Replaced MAF, no change. During the brief minutes it's actually running, it runs totally fine.

Finally just abandoned the damn thing in a lot, got a ride home, and had it towed home (i was begging the tow truck driver to dump it in a pond or off a cliff at this point). I noticed with the hood up, that when it would start then die, puffs of smoke would rise from the intake, but couldn't pinpoint exactly where. I am thinking this may be related to the fuel pressure regulator, the fuel pump relay, or bad injector(s). I also now notice a very strong fuel-ish type odor while it's idling, but it's not a straight-up gas smell- it's like it's running super-rich.

Any ideas? I'm totally frustrated, and as soon as it's fixed, i'm selling it and getting an LT1 six speed, hopefully vert.

Thanks!

 

check your mas sensor relay if you are throughing code 34 I belive this is the problem

good luck

 

:igree:
Replace the MAF sensor relays to try and cure the supposed MAF problems.

The lack of fuel problem could be due to a faulty oil pressure switch (behind the intake base near the dist). This switch is the only source of power to the fuel pump once the engine is running.

 

85's don't have any MAF relays to replace, they have a Burnoff module behind the breadbox. Do you have any codes? Could be the O2 sensor. It sound like it runs initially because it is in open loop. After a period of time, you enter closed loop and the ecm uses sensor information. If one of the sensors is giving wrong information, you get the wrong amount of fuel. Also, check all your fuses.

 

That is not correct. The fuel pump relay is the primary source of power to the fuel pump. The oil pressure switch is a back up to the relay, in case of relay failure.

RACE ON!!!

 

Haven't scanned for codes since i got the car home (im out of town for 2 weeks), but never saw the check engine light thrown, plus the last garage that hooked up the scanner would have mentioned any codes. But, if I remember correctly, if you do the ground on the ALDL that makes the codes read out on dash, it puts the car in open loop. I tried that to limp the car home, exact same problem. I checked fuses related to ecm and anything fuel related, but they were fine. BTW, what are you referring to as the 'breadbox', and would the MAF burnoff cause this type of hell?

 

Mine did the same thing and the mechanic at that time tracked it down to being the HEI module, he put a new HEI module on in and it never happened again

 

the breadbox is that huge pad on the passenger side where the air bag is supposed to be... The MAF burnoff module is behind it... just prey its not that because it's ungodly expensive... I've never heard of anyone having to replace it though, so I doubt that's your problem.

 

If the MAF burnoff is bad, I should get a code 36 (i get home this weekend and will check), which would have thrown the check engine light- but that never happened.

So assuming no code 36, should I possibly be looking into the fuel pressure regulator? The pressure was ever-so-slightly low, and the exhaust smells really strong like raw fuel or something.

Also, I cant remember off the top of my head, but I did replace the ignition several years back with the MSD 6AL, and I can't remember if a new HEI module was part of it. I'll have to check when I get back.

In my amateur opinion, all symptoms point to the fuel system, but I'm open to any suggestions.

Thanks

 

PICK UP COIL.... Inside the distributor...in the center is a pick up coil...when those flake or go bad thats exactly what hapens...I cant remember the exact test procedure...I know 1 wire is white and 1 green..it plugs into the ignition module... 1 of those wires OHMS to infinity, the other to a specific value.. if you use the range that a haynes manual has and its on the outer bounds replace it>>haynes/chiltons uses a really loose value for that.. Ill see if I can find the specs on line... Its easy to test, and pretty easy to replace but requires distributor removal and distributor disassembly..

 

The ignition module might not be bad but the symptoms you describe are the problems a defective one will create. Pull it out and have it tested at Autozone, Pep-Boys, Advance Auto, etc. Costs nothing except a few minutes labor and if it tests good it eliminates one possible trouble source. If it's original equipment just that much reason for checking it.

Instead of changing parts until it runs, get out the shop manual and start testing the items that could be the cause of the problem. It's a whole lot cheaper.

 

Definately agree, should have mentioned it in my other post. We had an older Dodge mini-van a few years ago and it had the same kind of problem. Turned out to be the pick up coil. Most good parts houses will recommend changing out the pick up coil when you change the ignition module.

 

I agree it's ignition. Sounds that the fuel smell is from it not burning properly. HEI module at first then coil.

Good Luck

 

Assuming this is the coil we're talking about, when i put the MSD in, the this was taken out and replaced with the MSD Blaster coil- can the MSD be tested by normal parts store?



Also, i'm having trouble remembering what the hei module looks like and is located.

 

HEI module

 

My 85 did almost the same thing and after weeks of searching a guy suggested changing the ECM. I decided to do just that and all was well. What was happening is that the ECM was fine as long as it was cool outside but as soon as it was a warm day it would heat up and cause problems like yours. Put some ice in a baggie and wrap a towel around it and place it next to the ECM. If your car runs ok you will have the problem figured out. About the only thing I can come up with to try that is free. My car did not throw a code with the bad ECM.

 

A quick tap test on the ecm might be a good idea also. Drop the ecm down and with the car running, tap the case with a screwdriver handle and see if the car stumbles or cuts out.

Most bad ecm's are really just broken solder joints inside (one of the reasons temperature an have an effect). Tapping the case will simulate the jarring from driving. Takes only a few minutes and costs nothing to do.