94 Hard start
 

New to this forum, new to Cummins. I purchased a 94 for my Son 2 months ago (125K miles). It ran perfect until a week ago. It now is hard to start, but once running, seems to run ok. When we try to start it, it fires once and dies. If you keep trying to start it, it will eventually run on the 4th or 5th try. I believe it's sucking air, my Son thought it was the fuel filter sucking air. We replaced the fuel filter, cracked the injectors to bleed them, and after that it fired right up. We let it sit for an hour, and it hard started again. Are we on the right track thinking it's an air leak. if so, where should we start looking?

Thanks

Look over the entire fuel system with a fine tooth comb for leaks.

also check the fuel shut off behind the injecter pump,check to see if it sucks up with the key on, these can hang up and be intermitent.

Checked all the lines from the tank, to the injectors, don't see any visable signs of anything leaking. Checked the lines with the key on and lift pump running, checked the lines with the engine running. Did find a bolt missing on the AFC housing, replaced it, but still does the same thing. Is it possible that the lift pump itself could be loosing pressure and sucking air???. Tried starting it this morning, and it took 7 tries before it would keep running. Again, once it's running, it runs fine. The longer it sits, the harder it is to start.
Thanks

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Another question in reference to gmlent's comment. I do see that the boot on the fuel shut off solenoid it torn, will that cause a hard start condition?. How can I test the solenoid to see if it's working?
Thanks

The boot can come apart and get stuck around the rod causing it not to pull all the way in. so turn key on and reach in and push up on the rod, and see if it starts, my or my not be the problem.

Back to square one. I pressurized the tank to 15psi, no visable fuel leaks. I removed the fuel heater, still hard starts.

Question: When I pump the primer button, shouldn't it get harder to pump (it doesn't)?. Also, when I pump the primer, it almost sounds like air is being pumped out somewhere between the p-pump and the engine block (under the AFC)?. It's tough to see in there, but I don't think it's the return line, it appears to be fine. Is there anything between the p-pump and the block that could cause this sound when the primer is pumped?

bump

i would pay close attention to the fuel lines between the frame and the tank. thats were mine when bad at. the rest of the line was in decent shape. took me awhile to find the leak but i did..... replaced the lines with rubber and issue was resolved! hope this helps:tu:...also may wanna check your overflow valve... there cheap and will cause hard start when they go bad.

my step dads truck did this it would start after alot of cranking or alot of trys, get some contact cleaner ( i belive thats what he used) to help start it. he had a bad injector but his is also a 03' just an idea, or pull the injectors and have them tested

park it on the steepest hill you can find nose down overnight then see what happens when you start it the next day. if it starts fine then you definately have fuel bleeding back.

I tried all of the suggestions above, nothing worked but I just figured it out this morning (I'm a dumba__). The fuel shutoff solenoid!!!! I had my wife turn the key to crank, and the soleniod pulled up, but as soon as she let off the key, it wouldn't hold open. I checked voltage at the wire connector, and the relay, and voltage was good (both the hold terminal and the push terminal). I pulled the solenoid off and the boot was melted to the plunger shaft, so it would pull up when cranking, but it wouldn't hold open when the key was released due to all the gunk on the plunger. I pulled it apart, cleaned the shaft and housing with brake cleaner, re-installed it without a boot, and it starts right up. Easy fix (ordered a boot from Larry's today), just wish I tested the solenoid before replacing the transfer pump ($160). Anyway, anyone out there with a hard start probelm, please read this and learn form my mistakes. It's easy to test the solenoid for operation, and should be one of the 1st things diagnosed if you have a problem with the engine starting.

good job do all years of cummins have the fuel shut off solenoids i have a 01 that did that

Thank's lunk, though I'm not so sure about the "good job" part, I appreciate it anyway. gmlent hit the nail on the head, I just didn't take his advise regarding the fuel solenoid cause I was convinced it was an air leak, dummy me. As far as your 01, I'm not qualified to answer that, but others may chime in. I believe yours is all electronic, and has a different shut off system.

change the ofv, it is prolly bypassing the fuel