Strange Engine Behavior

[BCFAST]

OK, here goes: Ive been having problems recently with what "sounds like" a missing cylinder after installing 370's. The problem persists now even after changing back to the 215's. This morning I made a stop at an office building... was gone from the truck for 30minutes. When I re-started, the starter selenoid hung up, and then after getting that unstuck, the motor died and wouldnt re-start. It would crank, but not fire. I pushed the primer about 5 times and the motor started and continues to run fine. My questions are: in your experiences, is this a lift pump problem or an injection pump problem? Do you think the no-start and the "miss" are related? What can I do about the hanging starter, as this is the 5th or 6th time it's happened? Thanks guys.

 

[Joe G.]

It may be a bad overflow valve. Check your fuel pressure. Then squeeze the hose on the return line and see if that makes much of an affect on the pressure.



Check the contacts in your starter solenoid. It's pretty simple to take off. 12 pt 10mm wrench for the screws that hold it on and two wires to take off. If the contacts are ok, then check the fuel solenoid relay.

 

[BCFAST]

Thanks for the reply, Joe. Sadly, I have nobody near that will work on this truck... Cummins says they cant cause it isnt stock, and there arent any private garages I know and trust, so I'm on my own with this. Where is the return valve?. . at the filter? If its bad, are they expensive/difficult? What do I do about a pressure guage? Thanks!

 

[Joe G.]

The return valve is on the engine side of the injector pump just about even with the first delivery valve. If you remove it make sure you cram some rags between the pump and engine to catch the two washers.



For the pressure gauge I took illflem's advice and tapped the fitting to 1/8" NPT on the side of the injection pump where the line from the filters goes. I got a pressure gauge and snubber from Grainger. The snubber was not quite enuff to dampen the pressure spikes so I also installed a needle valve. From that to the fender well I used a grease gun hose. Then a gauge tubing kit from NAPA to get to the dash.



For a quick test of the return valve you can squeeze the return line hose with vise grips near the fuel filter and see what effect that has on the pressure. If it comes right up then you probably have a return valve problem. If it doesn't then look for a plugged filter or lift pump problem. If the pressure comes right up let go with the pliers right away.



I think Piers has the best price on return valves.

 

[BCFAST]

I have had that fitting apart before. I didnt think that was the return, but rather the fuel pressure regulating spring. The guage assembly sounds like a PITA.

 

[Joe G.]

That's where the pressure spring lives. Excess fuel is returned to the tank from there. There is another return line from the injectors. It goes to the input fitting of fuel filter.



The gauge is kind of a PITA but not too bad. More of a problem mounting it inside the cab than installing the plumbing. That was pretty easy since everything is easy to get too.

 

[illflem]

BCFAST, you can also set up a temporary fuel pressure gauge on the fuel filter bleed screw but you need a $25 adaptor from TST. If you'd like I have temp set up you can use, just PM me your address.