Engine/Transmission (1994 - 1998) Will not Start - 1996

[DragonflyDriver]

52K actual miles so naturally at times it sits for a month or so (garaged).



Had it out towing a light load on Good Friday back in March with no hint of a starting problem over the 5 or 6 starting cycles I put it through over the day. Engine has always fired up really quickly. Tried to start it last week and it cranks well but doesn't even try to fire. I checked the fuel valve solenoid as told by many on TDR and it functions as it should. I was really hoping that was the problem. Tank is about 3/4 full (or 1/4 empty -- depending on your mood).

Anybody have a short list of things to check next? I ran through a bunch of search results posts but most just covered the solenoid. Thanks in advance.

 

[mfburns]

I think you need to check for fuel flow. If it turns over it should start if its getting fuel. The compression ignites the fuel. Are you getting smoke out of the exhaust while you run the starter? If not you are not getting fuel. Then depending on your skills you can play with the fuel lines to and from the injector pump but be careful, fuel is under very high pressure. First thing I would do is drain fuel filter and check for water, then crank engine to see if you have fuel flowing. Then try to track from filter to injection pump, then to injectors. I have never done this so I will not provide any advice on how to do this.

Are you sure the fuel gague is correct?

 

[DragonflyDriver]

The gauge is correct. I had filled it not long before I last drove it and the use has been local and not much. I drained some fuel from the filter and it looked okay. No leaks detected from hoses either.

 

[Joe G.]

You can't see an air leak. Your fuel heater may have burned up. You may have had a line break at the fuel module. You may have got a bad tank of fuel. There are other possiblities. Email me at -- email address removed -- for my write up on the 12 valve fuel supply system. How it works and how to fix it.

 

[CEdwards]

Read this post after getting Joes write up. I just went through the same thing.

https://www.turbodieselregister.com...-hard-start-need-help-getting-frustrated.html

 

[Joe G.]

Yeah, there is no rule that says you will only get one air leak at a time. You may have a bunch of them and the crazy thing will still run. Sort of.

 

[DragonflyDriver]

I hear you guys. But this thing always fired up almost instantly. Never been hard to start. The last time it started was no exception.

But I will be trying the suggestions shortly.

 

[Vaughn MacKenzie]

Dragonfly, next time you have this problem try going under the hood and pumping the primer button a few times. If you have mostly air in the line the primer will be fairly easy to push. When primed with fuel there's a fair amount of resistance, and when you're pumping it aggressively you should hear fuel swishing past the overflow valve at the front of the injection pump.

Another thought, if you have someone to help you, go under the hood & put a 2-liter bottle on the end of your fuel drain, then have someone crank the engine. Don't open the drain valve until right after they start cranking. . . you should get a good rush of fuel, and no air unless you have a leak or are losing prime.

 

[DragonflyDriver]

Tonight, I started pumping the primer bulb. Ended up pumping for a few minutes as it seemed to not be offering too much resistance. I started hearing a high pitch squeak that seemed to be coming from the 7100 toward the front of the engine. No idea if that was air bleeding out or what.

The sound didn't change after 30 more pumps so I decided to try a start. I let it crank for about 4 seconds--nothing. I remembered reading about someone having to give a little throttle for one to start so I tried that next. The second I touched it she lit. I let off the throttle and let it run for a few minutes. Turned it off and started again without the throttle--no problem. May have been a coincidence that it worked when I hit the throttle.



So is a month normally too long to go without starting the Cummins? Does what happened warrant further troubleshooting or is a once-a-week start enough to keep this from happening? I'm guessing it depends on what exactly caused my particular situation.



Thanks to all for your help.

 

[Joe G.]

You an either set the idle up a little bit or get in the habit of starting with a little pedal. I do that.

 

[CEdwards]

If it doesn't start immediately after sitting all night tonight then you may need to look further into it. If your idle seems so low that it can barely run then lookup how to adjust it. It is pretty easy, it's just hard to see. It's hard to say if it's just the idle without being there. If it winds up being a air leak in the fuel line then you should fix it before it gets worse and leaves you walking.

 

[DragonflyDriver]

Well, it loses prime in under a day. No start tonight, with or without throttle.

 

[mfburns]

I had that problem several years ago. It was a leak in the fuel line. Air gets in the line and it cranks a lot with no start, then I tickle the pedal and it started. May run a tad rough for a second or two then fine. Shut it down for awhile OK shut it down overnight hard start. Check the connectors on the fuel line and return line to the tank. Some of them leak air into the line. I read a thread in here how to put pressure into the fuel line to force fuel out of the fuel line, you can't see air leaking into the fuel line. Not sure what the thread title was. Try a search or maybe somebody can provide advice on this.

 

[DragonflyDriver]

When it started the other night, it idled normal and didn't run rough.
Does that change anything in what I should look for?

 

[CEdwards]

It will run smooth as glass and still be pulling some air in with the fuel. I'm not an expert on injection pumps but I don't think this would be that good to drive it for months on end with air entrained in the fuel. The only way to solve the problem is to eliminate each possibility for a leak until you find it. Start with your rubber hoses, especially if they have been on it for a long time. When changing my hoses last time I disturbed the quick disconnect and caused a bigger leak. If you want to test the entire suction line then get some cheap fuel hose at the parts store. Doesn't matter if it's rated for diesel, it's only for a test. Get a bucket of diesel, stick one end in the bucket. Get a 3/8 hose barb by 3/8 pipe. Take the steel line and fitting out of the top of the prefilter assembly. Install the hose barb and put the hose on it. Prime it, start it, let it run and leave it overnight. If it starts the next day you have a suction leak. It still won't tell you exactly where it is though. The only way to do that is take the pump and lines off and test it for leaks with air. Or just start replacing lines. There is no doubt you have a leak somewhere.