M1090 seems to be starving for fuel under any load

My M1090 seems to have very low fuel pressure at the IP as it almost stalls under any load. It acts like it just isn't getting enough fuel. I've changed both filters with no change at all. It runs at wide open throttle while sitting still in neutral but as soon as I start to drive it empty, it won't even get out of 3rd gear without bogging down. I can stop put it in neutral and it'll eventually rev back up but the process is repeated as soon as I take off again. Is there a screen on the pickup in the tank? I've thought of changing the rubber fuel lines although I don't see any seepage. I just picked this truck up so no idea how long it's been like this. Any other thoughts would be greatly appreciated.

Is the air filter good?

It appears to be. I've also noticed that if it sits for a couple days, it sounds like it's getting some air in the system when I first start it. The primer bulb doesn't feel tight either after it sits.

Sounds like an air leak. Super bad for injection system.

Check the fuel lines, age causes them to crack and suck air.

I'll change all the lines. The supply line appears to be newer than the others but also looks smaller in diameter? What is the correct size supply line? Can't imagine that it should be smaller than the return.

Crownfire,
I just went through this myself and Steve in Kentucky also. This is what I did. Hose is 3/8 inch line and -6 AN fittings. I used pushlock style fittings and hose so I can make my own hoses. I also found that the Primer bulb was leaking. You can get it all at your local Parker store. They usually have the primer housing and filter set in stock. However, they don't sell the filter housing as a kit with the 24v heater element. But you can use your old one. After I installed two of these filter primer units (they would both leak air) and the fuel would return to the tank. Here is Parkers tech quote, "these primer housings are NOS. We don't sell many of these units anymore and the units that we do sell are probably on the shelf for about 10 years. We recommend that anyone who replaces or uses this unit also put an inline check valve at the tank. That way the fuel will not be able to drain back." End quote. So, until I installed the check valve I had issues starting the truck. I had to prime it every time it sat for a few days. I installed a summit racing inline check valve part number SUM-220192B. You will also need two pushlock -6AN fittings to put in the hose and then attach the check valve. Once I installed this check valve I've had no issues. Sucks to have to deal with these primer bulbs leaking air but it is what it is I guess. And they are not cheap! Good luck and hope you get it running soon.
Eric 619-952-4337

my cat guy said ditch the filter and housing and put on a racor with no primer than add a cat pimer working on getting part numbers together now

snowtrac nome said:

my cat guy said ditch the filter and housing and put on a racor with no primer than add a cat pimer working on getting part numbers together now

Click to expand...

I was wondering if you had done this to yours. I remember you mentioning it in another post. Question I have where would you mount the primer?


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Man of few words

M1081 LVAD

I should have stated clearer in LAST post that I did replace my filter/primer with the RACOR unit. I purchased it through Parker store. They carry RACOR.

Duckworthe said:

I should have stated clearer in LAST post that I did replace my filter/primer with the RACOR unit. I purchased it through Parker store. They carry RACOR.

Click to expand...

Did you replace with the nos house with the primer or without primer.


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Man of few words

M1081 LVAD

With the primer

I looked at the CAT primer and it was pricy! It isn't a primer bulb but rather a push pull style primer housed into a metal housing. I didn't go with it as I didn't have the time where I was located to reconfigure the system. You would need fittings, mounting brackets, and whatever else I didn't even think of. So I went stock. But it would be the way to go.

Duckworthe said:

I looked at the CAT primer and it was pricy! It isn't a primer bulb but rather a push pull style primer housed into a metal housing. I didn't go with it as I didn't have the time where I was located to reconfigure the system. You would need fittings, mounting brackets, and whatever else I didn't even think of. So I went stock. But it would be the way to go.

Click to expand...

I think that what snowtrac nome was getting at. I’m not familiar with all that is needed to do the switch.


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Man of few words

M1081 LVAD

I'm going to be robbing one off a 3306. with a water separator. the cleanest install would be off a wax c-7 but im afraid it will stick up too far as the primer pump sits on top the secondary filter housing. once installed I wioll give an update with my pump install with required fittings and hoses.

I've replaced all the rubber lines and notice little to no change. I have a new water separator ordered. Local Parker Store told me they couldn't get it.

crownfire said:

I'll change all the lines. The supply line appears to be newer than the others but also looks smaller in diameter? What is the correct size supply line? Can't imagine that it should be smaller than the return.

Click to expand...

Sounds like time to break out the manual do some reading. Did you add the check valve Racor suggested that Duckworthe mentioned?

I’ll be adding it to mine when I start working on it. Have you inspected the fuel for algae or other contaminates.Don’t remember if you said having fresh fuel in the tank. Just a thought


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Man of few words

M1081 LVAD

I've not installed a check valve yet. I'm waiting for the water separator base to come in. Fuel is clean and free of algae. I've pulled the pickup tube as well. No obstructions from the tank to the injector pump. I'll be putting a pressure gauge on it to check the condition of the pressure regulator. If all that doesn't work, I'll quit throwing parts at it and take it to a Cat shop where they can diagnose and repair it. I do appreciate all the helpful ideas to this point and will post what actually fixes it hen I'll move on to the alternator and CTIS. Will probably be looking for an alternator and CTIS ECU based on preliminary troubleshooting out of the respective manuals.

Did you get it fixed ?

Fuel issue has been resolved. The #5 injector seat was leaking by causing the fuel to become aerated. Reseated all the injectors and adjusted the fuel rack. Runs great now.