P32 MH Engine Dying Abruptly

[1969SSCamaro]

I have a 1995 Georgie Boy MH on a P32 chassis with 454 eng with TBI. MH only has 37,000 miles and spent the last several months doing extensive maintenance; coil springs, airbags, ball joints, fuel filter, changed/flushed ALL fluids, check spark plugs, etc, etc. Recently took it on maiden voyage that was 360 mile round trip. On the way out and on the way back, the MH all of a sudden died, usually on the highway driving at 60mph. I would shift into neutral and it would fire right back up. This happened about 8 times total; 5 times on the highway, 2 times on surface streets (maybe 35mph) and the last time at almost a dead standstill pulling into the driveway. Everytime it died, it happened instantly with no hesitation or intermittent cutout. Environmental conditions were benign with 75-80 degree temps, no rain, water, etc. There did not seem to be any coorelation to it dying; rough roads,hard braking, hard acceleration, it just inexplicably dies. I am at a loss in terms of how to troubleshoot such an intermittent problem. I suspect it is ignition related, ECM, coil, etc, something having to do with spark plugs not firing? Any suggestions on how to move forward. There appears to be connector on driver side for the computer, but it is an older style connect that is not compatible with device I have. Does anyone know if I just need to get an adapter, or do the older computers required completely different device?
Thanks,

[Stim]

My first guess is ignition pick up in distributor.
Second guess fuel pump relay/circuit. The oil pressure switch could be acting up. See if it is covered with oil/leaking.

[mrdennis60]

I had a Pursuit on a 1999 workhorse chassis that had exactly the same problem. I would be driving on the interstate, engine would just quit. Before I could get off the road it would restart. My problem turned out to be the ignition module which was located on a bracket top rear of engine. My research at that time indicated high engine compartment temperature do to design was a contributing factor.

[turbojimmy]

^ What he said.

Based on the description - instant failure versus stumbling, stalling, rough running - points to an electrical failure of some sort. Ignition coil is a good bet IMO.

[Daveinet]

rgatijnet1 wrote:
You have done a lot of maintenance so I would look for something that could have loosened a plug, or frayed a wire, that shuts off power to the ignition. You don't say if the dash goes blank which would indicate a loss of power to the main control panel or if just the engine quits which could be a loss of power to just the ignition/ECM circuits.
Go back over any work that was done around the engine compartment and 12 volt circuits that keep the engine running.

This would be my first bet as well. Yes, you can look at the OBD1 port, but most likely you are loosing power somewhere.

If you really want an OBD1 cable, you can build a circuit for about 15 bucks in parts, however finding a laptop that still has a serial port is rare. Find a USB to serial adaptor that is tolerant of the odd baud rate is hit or miss. At this point in the game, you are probably just best off to buy one here:
http://www.aldlcable.com/products/aldlobd2u.asp
Once you have the cable, the best program for reading the data is:
http://www.tunerpro.net/downloadApp.htm
This program is just a generic skeleton that requires a plug in that will interpret the data, which you can download here:
http://www.tunerpro.net/downloadBinDefs.htm
Download the datastream definition for $OE. The program is mainly designed for tuners so it has a bunch of features for burning chips, and other things you are not likely to use. However it is the most comprehensive software out there. The learning curve is pretty steep at the beginning, but once you understand the concept, it all makes sense. Eventually you can create your own dashboard layout, so parameters are easy to see. This is what I run and have burnt several chips for my ECM.

One other possibility is a bad ignition coil, especially if heat aggravates the problem. Bad coils will usually start right back up again, but die quickly. Once the engine cools, then they recover and work fine till things heat up again. They do not give any warning, and normally do not throw a code. If you suspect the coil, when it dies, you can unbolt the coil from the engine and isolate it from ground. If the engine runs, but then dies as soon as you touch ground, then you know the coil is shorted.

I should also add that it is highly unlikely the ECM is bad. By 1993, the ECMs were pretty stable in GM vehicles.

You do not have a crank position sensor in that vehicle. That is only used for sequential FI. Since you have a TBI, the ECM does not care what position the crank is in. It just monitors the Dizzy to know when to fire.

[othertonka]

My guess is a weak fuel pump. I had a 2000 Fleetwood that quit on me three times at different times and the only code it set was for a "lean fuel condition". replaced the pump and it worked fine until I traded it in in 2004. Might want to get a fuel pressure gauge and check it out.

[darsben]

AS has been stated in other threads. 454 engines are notorious for collapsing vacuum advance tubing. Please replace the tubing and retry

[enblethen]

You can read codes by jumpering two pins on the connector and then read the flashing engine light. This is very early OBD II and late OBD I. I haven't found any one that has the OBD I.5 reader.
The older ones will not show all the codes like the OBD II does. Even some of the codes are not correct.
Terminals "A" and "B" need to be jumpered using a short piece of wire or paper clip.
Pin a is on flat side of connector toward the bottom and B pin is just above it.
Insert jumper, then turn on ignition switch. First code is 12 and will flash three times, then any code will flash three times each.
Could be something like the Crankshaft position sensor, camshaft sensor
I would be more looking in the distributor. Possibly the coil pickup or the ignition module. Look for loose connector.
PM me if you want me to scan page out of my book. We are leaving tomorrow for roadtrip.

[allbrandauto]

that connecter is old obd1 12 pin connecter you could go on ebay and buy a used scanner for this mh very cheap all obd1 gm scanners will work I like snap on scanners it would be worth its weight in gold with what it can do for you some times computer can go bad start mh up and tap on computer see if it cuts out

[the_bear_II]

Some autoparts stores have the OBDs and will let you use it to diagnose a problem in hopes they can sell you parts.

Hopefully someone can shed some light on the cause.

Maybe this forum can help:
http://www.dieselplace.com/forum/6-other-vehicles/9-gm-gassers/

[rgatijnet1]

You have done a lot of maintenance so I would look for something that could have loosened a plug, or frayed a wire, that shuts off power to the ignition. You don't say if the dash goes blank which would indicate a loss of power to the main control panel or if just the engine quits which could be a loss of power to just the ignition/ECM circuits.
Go back over any work that was done around the engine compartment and 12 volt circuits that keep the engine running.