real time help needed -cummins lift pump failure

[wanabecruisen]

I'm thinkin my lift pump just failed on my 99 cummins 5.9. Stopped for fuel this morning (had less than 1/8 tank but no running issues before stoping). Pumped my fuel and got ready to leave and no start. Thought I had run it too low of fuel so I tried the prime thing several times with no success. I tried bleeding fuel from my filter canister and did get a little out of it at first but now nothing. I have a pressure gauge on the canister and with the pump running (key in the start/on position) I'm not getting any fuel pressure at the filter and no fuel if I open the separator valve.

I've done a good bit of searching but never herd of one dieing quite this way. What do you think - new fuel lift pump time? Thanks in advance for the help.

[FullsizeYota]

You may have lost the prime that you once had. The injection pump on these trucks WILL suck fuel from the tank but it is very hard on them.

probably lost prime from no fuel, inj. pump wont restart the prime.

Sounds like you need a new lift pump.

[Mechanos]

Crack the supply fitting loose at the VP and bump the key to activate the lift pump. This will bleed air out of the system and also let you know if your lift pump it working. Sometimes even this isn't enough and I've had to crack an injector line loose to bleed the system.

[wanabecruisen]

Originally Posted by Mechanos

Crack the supply fitting loose at the VP and bump the key to activate the lift pump. This will bleed air out of the system and also let you know if your lift pump it working. Sometimes even this isn't enough and I've had to crack an injector line loose to bleed the system.

Would opening the separator valve on the filter canister and activating the lift pump not result in some fuel being delivered to the canister? I can clearly hear the lift pump running but no fuel at the filter.

I'll try the cracking the fitting on the VP next.

Thanks for the suggestions.

[tophvytoy]

Sounds like clasic lift pump failure. If you are not seeing fuel press. at the filter you will more than likely not see it at the IP. Just because you hear the pump running does not mean it is pumping fuel, as it is a rotary vein pump. If you do determine it is the lift pump I would recomend going to a F.A.S.S. pump. You can purchase a direct replacement that will plug into you factory wiring and mount back by the tank where it should have been in the first place. These are a little noisy but once you start the truck the noise mysteriously dissapeers ! lol . I know of several of these pumps in opperation and all work well. Another thing, get a fuel pressure guage or light. IMO this should be installed on a 2nd gen. 24 valve truck before you purchase your 1st tank of fuel.

[v6toy4x]

I have been running the FASS stand alone pump for several years now and it seems to work very well!! It is a bit noisy.

[wanabecruisen]

Up and running again. Hat to get 'er back on the road so went back with another Carter for now. What a pain to prime that thing!. I'm going to look into the FASS system cause priming that damn thing really showed me how hard that pump has to work to pull fuel from all the way back to the tank! BTW - pressure is not at just over 9psi at idle and 8psi under load. Not great but better than I had before.

On a related note - I puled the inner finder liner to change the pump. Anybody do this and have a line on the little plastic rivets to put the liner back in?

[mondtster]

Originally Posted by wanabecruisen

I'm going to look into the FASS system cause priming that damn thing really showed me how hard that pump has to work to pull fuel from all the way back to the tank!

Realistically, it shouldn't have to work any harder than any other carbureted car's mechanical pump on the side of the motor does.

My suspicion is that you had air in the system which was fighting you. Air is compressible, fuel is not. I go through a similar ordeal every time I change a fuel filter on my 12v truck because it is compressing the air that is in the system.

Originally Posted by wanabecruisen

On a related note - I puled the inner finder liner to change the pump. Anybody do this and have a line on the little plastic rivets to put the liner back in?

Most larger towns have an auto body supply store. Try there, or at an auto body shop.

[Mechanos]

Originally Posted by wanabecruisen

Up and running again. Hat to get 'er back on the road so went back with another Carter for now. What a pain to prime that thing!. I'm going to look into the FASS system cause priming that damn thing really showed me how hard that pump has to work to pull fuel from all the way back to the tank! BTW - pressure is not at just over 9psi at idle and 8psi under load. Not great but better than I had before.

On a related note - I puled the inner finder liner to change the pump. Anybody do this and have a line on the little plastic rivets to put the liner back in?

While youre looking into fuel systems... don't just focus in on one. There are several out there to choose from: FASS, AirDog, etc. for electric pumps and Fuel Boss, Mitusa for mechanical lift pumps. I put a Fuel Boss mech. pump on my '01 CTD about a month ago and LOVE it. It's nice to see the fuel pressure actually rise instead of drop when you put your foot to the floor.

[tophvytoy]

A mechanical pump for a carb. engine is usually a diphram style not electric rotary vein. Electric pumps were designed to push not suck ! These can't be compared to diaphram pumps.

[Mechanos]

Originally Posted by tophvytoy

A mechanical pump for a carb. engine is usually a diphram style not electric rotary vein. Electric pumps were designed to push not suck ! These can't be compared to diaphram pumps.

WTF are you talking about???? This thread is about diesels, not carbed engines. And the mechanical pump I'm referring to is a belt driven gear pump, not a diaphram pump, and will suck the chrome off a door knob.

[tophvytoy]

Hey mechanos you need to learn to read better. Read mondster's post. The little one right before mine & you might get a clue.

[weedwacker]

I bet 90% of the dorks that put these mega fuel pumps in never drop the tank to clean the tank strainers. Also the last strainer that attaches to the fuel line in the tanks has an ID opening of about 1/4 on an inch. It can be reamed out to near 3/8. Clean the strainers ream that hole and your fuel pressure will improve.

[tophvytoy]

Just drilling out the bajo bolts before & after the filter and at the IP will gain you 2 to 3 psi.