12V won't stay running longer than a few seconds...

[Rogan]

My buddy just picked up a '95 3500SRW. It ran fine, but all of a sudden, it now will only run a few seconds (3-5) at a time. He replaced the FSS for some reason. I told him to check the filter, check for leaks (sucking air? ), lift pump, etc. He doesn't have a fuel pressure gauge, so I don't know what the FP is doing.. Anyone heard of this, a remedy, etc? that I havent mentioned to check yet?Thanks!

[flagmanruss]

It seems odd that it will fire at all & then not run after. I think you are on the right track with checking the fuel system. What else is there on a 12 valve? In any event, this needs to be approached logically. #1 Confirm fluel pressure? It might be getting just enough fuel to fire then dying when asked for more. Failed shut down solinoid? Bad switch? Inquiring minds want to know!

[ISX]

Check for air leaks! There really isn't much else, as long as fuel pressure is getting to the IP and the fuel shutoff solenoid is working, it should run. What is he doing to get it to run the 3-5 seconds? Just flooring it? When you prime the fuel system if 3-5 secs is all it runs then it is sucking the fuel system back dry, the lift pump isn't pumping or something is clogged or something is leaking.

[MnTom]

If this just started after the fuel solenoid change then check the solenoid to make sure it is adjusted properly. I had something very similar happen to a '98 12v I was working on. The solenoid was lifting just enough to allow it to start, but would fall a little and shut the truck off. Seems to me that the relay should pull up about 1 3/4", but I am going by memory here.

[Rogan]

Thanks guys. I'll have him look into it and report back.

[ISX]

http://dodgeram.org/tech/dsl/troubleshooting/12v_fuel_solenoid.html

[Rogan]

I checked it out last night. It was the FSS. I adjusted it and all is well now.

[MnTom]

I checked it out last night. It was the FSS. I adjusted it and all is well now.

Glad it turned out to be something simple!