Cummins ISC engines 8.3 cranks but won't start

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George V. McRae McRae Wrecker Service

4 жыл бұрын

2008 Peterbilt Cummins 8.3 ISC motor Cranks but no start no high pressure fuel rail pressure

Пікірлер: 29

@emmettboaz 3 жыл бұрын

I've seen this problem a couple of times. Often the pumps will meet the fuel pressure specs during cranking and the engines will not start. Change the low pressure pump and they fire right up. I think it's a weak spring in the pressure regulator so it won't build enough pressure during cranking to open the check valves in the high pressure pump head. If I ever see it happen I think the thing to do would be to shim the pressure relief and see what happens.

@williamsherman8484 3 жыл бұрын

You really seem to understand the Cummins Diesel, so I'll toss a question to you and anyone else out there. I've got a 2007 Diesel pusher Motor Home with only 6,000 miles since new. About a month ago, the engine decided it no longer wanted to start. It crank well; but no start. The fuel gauge shows "empty"; but I know there is at the very least 45 gal. in the 100 gal. tank. Checking we have found fuel is getting to the base of the high pressure pump; but not getting to the fuel rail. Is there possibly there is a fuel level signal being feed off the tank or gauge that is telling the ECM not to pump. The dashboard status is somehow also being told there is a low fuel situation going on, which I suspect is coming from the ECM as opposed to being directly tied to the fuel sending unit. Any easy way to figure out the "low fuel" problem. Sure hate to drop that 100 gal tank to get to the sending unit; that's a lot of work for a young man, little-lone for an 85 year old guy like me. Thoughts please.

@jameswade8432 3 жыл бұрын

If fuels dribbling or none at all from the HPP line to common rail its the HPP head. Most likely check valve, I soaked mine with atf and manually stroked the plungers a bit and she's worked flawless since

@Gary-dc2nm Ай бұрын

Power Service Bio Kleen . I purchase it at Tractor Supply wear gloves when putting it in your tank.

@juriegiliomee4555 Жыл бұрын

Do you have a part number for the gear liftpump? Seems to have the same issues

@gvmcrae Жыл бұрын

Sorry I don't

@loquillo453 2 жыл бұрын

I have the same engine my problem is that smokes a lot when I start the truck a lot of white smoke then smokes for 15 to 20 seconds then no more smoke

@jameswade8432 3 жыл бұрын

Ive got this problem right now i believe! After sitting all summer and trying to start it it would idle 20 secs and slowly starve n die, few cycles of lp and it start again and repeat. Replaced lp to no avail, today blew some air in the line to the tank and she fired up ran for 5 minutes and died! Both fuel filters were only half full of fuel after that. Blew some more air in tank line didnt help. Now it wont start! Good lp pressure at the low pressure check port but nothing coming out of the hp pump!

@gvmcrae 3 жыл бұрын

James Wade, seems to me if your truck started and ran for 5 minutes after you tried the air pressure trick one of two things either you have pinholes in your supply line from the tank or the same problem we had a bad low pressure pump. I don't mean the delivery pump which is electric I'm talking about the mechanical low pressure pump which really kind of fooled us. First I'd make sure that your fuel line will handle a vacuum test as well as pressure test. Try using a 5 gallon can of fuel and a brand new hose make a temporary connection to the engine and eliminate the fuel tank and hoses. If nothing changes with the fuel can sitting on the ground try elevating it above the engine. The only way your engine would run for 5 minutes is if the fuel filters were filling correctly.Good luck!

@jameswade8432 3 жыл бұрын

Ok, some more "play" time with this thing today! Jerry can hooked up, nice steady 10psi supply to the low pressure pump and almost nothing after the pump(filter head inlet from pump outlet). While cranking it only builds to 20. Could it be the check valvle inside the pump as you say not much to go wrong with the pump itself, explains no outlet psi.

@jameswade8432 3 жыл бұрын

Heres a great fuel system video. kzfaq.info/get/bejne/hJOCg8eDrZ3Yd6s.html

@jameswade8432 3 жыл бұрын

Ok!! Pump bench tests 60psi easy while hooked to factory fuel connecters and driven with a slow speed drill but put back into motor driven gear and wont go past 20psi!! Check valve looked ok.

@chsonnyboy5 3 жыл бұрын

Have you tested voltage to electric pump? Maybe that is eratic. Also c ould gear pump have small foreign particle in it? My rv has2 filters an i only change first one an always take apart. Learned many years from Case tractor first Diesels that there 3 filters -last one should last many thousand hours befor needing replacement. Reason for that is to not get dirt in fuel pump!