We have been working on a Dodge pickup with a 5.9 i think its a 1994. It has a primmer plunger on the lift pump on the engine. The problem is that if it sets for 30 minites it has to be pumped up agin. The lift pump has a good 20 pounds and every thing else seems good. I started it then clamped off the fuel line that didnt help. Could there be a problem with the injecter pump?
You check overflow valve.
Is this a new lift pump? Even if it is, I would swap it out. AFTER checking if the supply line from the tank has any air leaks.
No can i take it off and check it? No i put a gauge on it and it held presser for hours. I hate to throw money at it the pump is $175.00. It has a flat bed so it would be easy to check the line.
So, how can you pump it up if it's holding pressure?
You want to pump it up, it should hold pressure in the injection pump. It should positively seal until a greater pressure unseats it to leak off back to set pressure. Sometimes, on really rare occasions, the injectors allow air into return circuit which then siphons pump empty
Wheres pump guy at. He'll know what you gotta do
I forgot to say i had it off the engine when i tested it.
So, if you turn the engine to where you get the longest stroke on the lift pump manual lever, and pump it up till lever falls limp. How much pressure showing at inlet of injection pump? Turn ignition to run, pump up again, what pressure do you show now. How long does that pressure hold? https://cppdiesel.com/cummins-3941156-vp44-overflow-valve-98-5-02-cummins/ Not endorsing, just the first info image I found on google.
I put a fitting in the out side of the pump. I dont have the right stuff to test it with the line hooked up i will try to get it riged up and test it.
Verify that the fuel transfer/lift pump supply pressure to the injection pump is within specifications. Normal fuel transfer/lift pump pressure specifications are 17 - 22 psi at idle and of 25 - 35 psi at 2500 rpm (no load). If supply pressure is less than 17 psi at idle or 25 psi at 2500 rpm (no load), restrict the fuel return hose by pinching the hose . If pressure returns to normal or above, replace the overflow valve with a new valve (P/N 04883838AA). The overflow valve is located on the side of the injection pump . Best I can do. Copy n paste from dodge service manual
5.9.. In-line or rotary pump?? Biggest failures on the inline is the overflow valve.. remove it & shake it.. if the spring is broken, there ya go.. SOMETIMES, more ofter than not, the spring in the ovflo vlv will get weak.. & allow fuel to drain back.. The other IS the lift pump.. AND the filter head.. the filterhead has a screen & checkball in it.. they rust all to hell..& the valves & piston in the LP/supply pump get scored in the alum. hsg. Only thing to do is replace BOTH the overflow valve AND the LP.. or do it 1 at a time.. Overflow valve can be purchased from a fuel shop.. just have the Bosch 10 digit P#.. 0 402 *** *** Have the engine S# when ordering the LP from cummins.. cuz there are 2 dif. ones..
It has a inline pump. I pulled the overflow valve and i could blow throw it i allso let it set with a little fuel in the bearing end and it leaked throw. I had the lift pump off put a gauge on it and pumped the rod by pushing it against the table top it went a little over 20psi and Held it there.I will try and rig up to test it while the engine is running.
U shouldn't be able to blow thru it.. that's the problem.. or 1 of them anyway. 2 417 413 083> bosch p#
That didnt fix it. Today i ran the fuel line into a bucket. Had to pump it up then start it after shut down 1 to 1 1/2 minutes bubbles came out of fuel line. The straner fuel preheater leaked some fuel at the wire plug in. elininated it bubbles went away still wouldnt go unless primed.Got the presser tester riged up on outlet of filter 15 pounds at idle 26 at 2000 rpms. Return line is hooked back into suction side of lift pump clamped it off at idle 60 psi.
On our 96, the fuel line between the filter and pump got porous. Changed and no issues. It was letting air in when the truck sat for a day. Cam
I changed out the line.I ran the return line and the supply into a bucket and it started every time. I also took the filter apart and looked at its seal and replaced some washers in the fittings.Then i hooked the return back up and tryed it agin it started. Then pressered up the fuel tank and it pushed fuel out the line. I then biowed back in the line it was clear. I then blowed in the fuel cap hose and with fuel line lowered down it siphon out of the line on its own. I put it back together and bleed it. It started but wouldnt start after seting 5 minites. I then back steeped every steep and it wouldnt start after seting until i got back to were i had both lines runing in to the bucket. i always get the air out and let it run for some time when i start it. If i had a check valve i would put it in the return line.
Did u REPLACE the overflow valve or just "work" on it?? {They're pretty expensive.} The check valves ARE the overflow valve AND the lift pump..
I replaced the valve. I have a new pump but havent put it on yet.
Today it fired right up. We had about 3' of clear line hooked to the return line runing in a bucket the end wasnt down in the fuel. I hooked the return back up and it was starting so we pulled it out side. Its down in the 20s today. After over 2 hours it had trouble starting. Monday i am going to replace the fitting were the return gos in.
I have been told that wix filters some time dont seal so i ordered a luberfiner filter.
That's not a variable you described when swapping lines from bucket to tank. Don't know how a part that had no impact, will help.
I think some were it has a opening in the fuel system that dosent leak fuel but lets air in when it shut off. I had seen this before. One time it does one thing and the next it does something diffrent. I thought it was sucking air in the return but from were some one has taped a hole in the suck side of the lift pump inlet fitting and run the line to that? The new hole isnt that great or strait so i replaced the fitting and used alot of sealer on it but that didnt help. Why can i put a 3 foot hose on the return and it will work? We have thought about runing the return back to the tank like factory but it was working the way it was. Why did some one reroute the return ? It was done when it was 2 years old before the now owner bought it. This thing has me stumped.One resone i am replaceing the filter is a good pump guy told me he had problems with them sealing.
I'm willing to bet you have your return line submerged in fuel, when you're in the bucket. That prevents a siphon break. I believe you're on the right path. You are getting air intrusion, the question is where. You replaced the overflow, correct, with good soft copper or aluminum seal rings. No chance of rust or paint chips preventing a good seal?
We had the line in fuel . It would start. So i pulled it out it started. The line is clear so i could see and was told by the pump guy it would suck back and it did a little but it would set over night with the line runing down hill over a drain pan and it would start but you could see it had fuel in it.
My boss has one the same year its been modified so it has extra lines and filters. I was going to service it one time it had leaks every were but he never noticed it .It started fine.
The only variable seems to be your tank. Is it difficult to get the sender out. Perhaps you have some junk stacking up in the stand pipe or debris plugging the inlet strainer. That doesn't explain the night time bleed off though. Do you have a grid heater or flame start? I have seen the flame start nozzle to the intake cause all sorts of shenanigans. Just something to look for.
Sorry, totally forgot your working on a pick up
Its has a flat bed so the pickup can be pulled. I ordered a filter yesterday from OR parts he said he could get a luberfiner filter and i would have it today.I went there early no filter they cant get luberfiner stuff? I went to the shop and blocked of the line from the tank to the engine at the engine and blowed air in the tank end. It had a break were the rubber clamps to the steel line. I replaced line bleed air out started it left for a hour it wouldnt start. I pumped it up tryed to start it in 10 minites no start. I pumped it up started it then clamped off return line started up ok. I pulled new overflow valve i could blow throw it and it wouldnt hold fuel on top of the ballbearing. Tomorrow i am going to the place were i got the valve and get a filter and valve. We fixed the grid heaters they work but its been in a heat building all but for one time when we had it outside a short time.
Its unfortunate you got a dud valve. Really glad you found it though. Too often we tell ourselves, can't be that, its brand new. At least you avoided that trap Happy new year
Dam.. that's some bad luck.. did u buy the part # I had given?? Did it come in a Bosch bag??
I got it from a local cummins dealer i dont know what brand it is. They are very good to deal with if they say they have had a problem before i may drive to the nearest pump shop it will be a 3hour trip.
Dam.. just googlewho> diesel inj. pump shops near me.. & getm to send u 1.. a lot easier than the drive. Did u try "back blowing" it>> u might have some real ****** fuel.?? sticking the ball..
I looked at the one i got and it was a bosch. I went to the place were i got it and looked at another it was just like the one i had it didnt seal. I got a luberfiner filter there and when i got back i replaced the wix filter and put the old valve back in. I started it and shut it off it started. It was 12:00 buy then so i pulled it out side. At 5:00 it started right up it was in the upper 20s today. The luberfiner filter looked just like the wix other than the seal. The seal fit alot better.I think all this time the filter seal was leting in air but never leaked fuel. The pump guy ask me right off if i was useing a wix he went off about wix filters. I will know forsure in the morning.
The fuel heaters cause air lock problems on the dodges. I've deleted a couple of them to solve air lock problems. Not hard to do. I usually take it off and saw it off till only the spacer is left between the pump and block.