studlybilly

Ok, over this past weekend I went to grab my breadtruck from it's current slumber. For the record, it has a '94 4bt 12v cummins in it. It's been sitting for 2-3 months (give or take). It ran fine when parked from what we noticed, but now will not start at all. Here's a list of stuff we've done to help diagnose it:

*Put 8 gallons of diesel in the tank just to be sure

*Ran a 12v power directly to fuel sollenoid just to be sure, also felt it clicking to make sure it was activating, not to sure how reliable that is.

*sprayed a little starter fluid in the intake a couple times

*Used the manual prime pump on the side a number of times.

The strange part is, at times when pumping the little prime pump, you could feel pressure being built up, but other times it was very loose and didn't seem to have fuel passing through it at all. I have a friend who is knowledgeable with diesels and he says that the lift or injection pump are more than likely fine being as it wasn't slowly dieing, just flat out wont start now. Any ideas other than pointing a gun at the hood and looking away?

John Faughn

Fuel pressure test , not comin for the injection pump to go , but LP & over flow valve - this is what makes pressure .

searcher

I am no expert since my Cummins has always started on the very first bump (knock on wood) but a Cummins requires a very strong battery to start. One that sounds like it is turning over fast enough may not be good. The fact that it has sit up a couple of months may have caused a weak battery.

The cam has to be in exactly the right position for the primer lever on the lift pump to work. I found out the hard way. I changed fuel filters and tried to prime, Reset to tdc and tried again. Went and ordered a lift pump. I then went out next morning and tried to prime without luck. I then barely bumped the key and got the primer working.

If all else fails then bleed the injectors. Good luck.

G1625S

Sounds like there's a slow air leak somewhere and that the injection pump is dry. You've got to crack the overflow restriction on the back of the pump (just above the shutdown solenoid) and prime it untill you get a steady stream of fuel. Even then, you may have to crack a couple injectors to get her to fire, depending on how much cranking you've done with an empty IP. Once she's running, start looking for air leaks in the fuel system.

studlybilly

Ya the starter fluid ordeal came from said friend. He mentioned air being in the fuel system and trying to get her to turn over so it gets things flowing. Would the system not bleed itself even after trying to start it a good number of times?

**EDIT** Just for grins, the battery was dying, but the motor was spinning over fast enough to fire, especially on the starting fluid, however it would only get a few seconds at a time from the dying battery. We were jumping it off so it would get 5 second of good spurts then start dying again.

John Faughn

1st things 1st , good battery , low voltage can cause all kinds of gremlins , not enough power to hold fuel solenoid , ect.
As for fuel leaks , wet on pressure side of LP - forward , 3 lbs air pressure in fuel tank to look for leaks on vacuum side .

edwinsmith

The injectors have a pop pressure which is several thousand PSI. The plunger in the injection pump has a very limited travel. If there is a substancial air bubble in the lines the air just compresses and takes up all of the plunger stroke and it never pops the injector. The air will then stay there forever until you bleed it off. Once you have the pump full of fuel, you can crack the banjo bolt on the back of the pump which comes from the return line (the lower one not the U shaped one which goes from the aneroid diaphram to the intake) and work the fuel pump lever until you get fuel out of the banjo then tighten it down. Then crack all of the injectors until you get fuel spray as you crank it. Then tighten the lines down as it cranks and it should start. Don't let the high pressure fuel touch your skin or it will cut you and this could be deadly.

In a totally dry system this may take quite a while so have a charger on the battery. The fuel likes to foam in the lines so the priming proceedure may be difficult. On mine it was a real bear because I o-ringed the pump and the system was totally dry.

Edwin

studlybilly

wow you guys have been a miraculous help, I greatly appreciate it! I'm gonna go do a run-down on that stuff today.

studlybilly

I dis-connected the hardline from the prime pump to the side of the head. Nothing was coming out. So either the prime pump took a spontaneous dump (doubtful I guess), or it's safe to assume the fuel line is clogged. The rubber fuel hose is very old and cracks easily. I've been told that they can easily break inside and clog up.

BearKiller

They also get real spongy and will suck together.

Did it try to hit on the ether??

Were you spraying the ether straight into the intake manifold, or just in the breather??

I have never had one fail to start, bleed, and then run, by taking loose the intake boot and spraying the ether straight into the intake, while someone else is cranking.

Don't drown it; just a squirt will do.

studlybilly

I sprayed it a couple to a few times. It would stumble over but not fire. There's no fuel period. I un-bolted the bajo bolt on the IP and nothing was coming out. So I undid the hardline from manual pump to the head (fuel filter location) and nothing was coming from there either. Given the way that the prime pump was acting, I'm fairly sure it's a clogged fuel line.

farmer0_1

as said earlier start at the tank and check for fuel getting to the next point in the fuel system the last check would be the inj line fitting at the inj. take alittle time and be persistent it will pay off in the end.

John Faughn

Put a small container of diesel inside the eng compartment , run a hose from it to the LIFT PUMP [ prime ] then operate the LP to see if it works , if it does get a gauge and check for pressure should be about , I do not have the spec in front of me , 22-26lbs at idle , 32-36lbs at 1500 rpm , if the pressures are low then you may need a overflow valve .

studlybilly

LOL We were talking about getting a 5 gallon gas tank to put in the cab, then cutting the hose from the tank to prime pump and just running it into there. My only intention is getting it to the scrapyard in whatever shape or form I can. I just want the engine/trans in it.

simplysmn

do what I did when I first did my swap I put a 12 volt electric fuel pump in the line just for that reason .when you chage filters all you do is hit the switch prime the system and bingo your ready to rock