'90 BMY - stumbles/cuts out on acceleration

[WillWagner]

You are absolutely wrong. Go look at TM 9-2320-272-23-2 WP 239, fuel system bleeding and priming. Items 6/7 ARE the bleeder for this pump. I have done this procedure a half dozen times.

I stand corrected, the MW did/does have a bleed, I forgot about that. Gotta say, in 25+ years, never had to use it, the Bosch inline pumps are self bleeding, put your foot to the floor and crank it. I thought about the older overflow valves. They had a screwed in plug that was shimmed thet was mistaken for a bleed. People remved the plug, lost the spring and shim and caused all kinds of issues. The system still needs proper trouleshooting done to it. Check for air and your pressures and see what you come up with.

 

[MontanaBighorn]

I decided to try to drive it down to my shop to get it indoors where it would be warm enough to work on it. I made it twelve miles just fine and then it started cutting out again and died. I removed the canister and it was full of fuel but just not making it to the injector pump. Despite my best efforts I couldn't get it to start again (hoping I didn't damage the injector pump now) and with it being 11 degrees outside I ended up having it towed ($318 to tow it eight miles) and at this point cannot dedicate anymore time to it until I catch up on professional obligations.

 

[MontanaBighorn]

After repeated failed attempts at trying to find the problem I sent the truck over to a local dealership. Initially they said the fuel filter wasn't seated properly but this was not the problem because if it was that would mean that the original filter that I replaced wasn't seated properly either, which I doubt. After putting a little more time in it they determined that the wiring going to the cut off solenoid had an intermittent short in it.

At this point I'm not real optimistic about it because I don't understand why it would only happen under heavy acceleration....but until it happens again I'll just have to hope that this fixed it. Here is a copy of the invoice with the mechanics explanation.

http://imageshack.us/a/img853/1674/pc9z.jpg

 

[doghead]

You could always manually override the shutoff(covered in the TMs) to eliminate that as the issue.

 

[MontanaBighorn]

You could always manually override the shutoff(covered in the TMs) to eliminate that as the issue.

This is my intent when/if it acts up again. I put about twenty miles on it last night without issue so perhaps he's onto something. One thing I did notice though is that when I turn it off now it takes about seven seconds for the engine to stop whereas before it was always instantaneous.

 

[WillWagner]

On a normal truck with this engine, there is an electric sol. that pulls in to put the rack in the pump to the full fuel/start position and de energizes to put the rack to the zero fuel/dump port in the delivery valves. Do these have them? If so, the issue you are describing COULD be from a failed shut off valve. The most common way they can fail is where the threaded rod/link is attached to the plunger in the center of the solenoid. Easy way to check it is to grab hold of it, the center shaft of the shut off valve, and see if it wiggles like the joint is broken where the shaft and plunger are joined together. The plunger also needs to be adjusted to, IIRC, 2 5/5 inches of travel. I might need to go look that up, it has been a bit since I had to mess with one. The attached pic has the FSOV, Fuel Shut Off Valve, circled. There should be no movement in the plunger shaft. And, just in cast these engines have the P, MW or A pump, the overflow valve and FSOV is the same. The gallery pressures are different though.