are 6.9 and 7.3 injector pumps interchangeable?

[rnh]

first off i've been reading here for awhile now and have greatly benefited and fixed many things on my truck because of you guys. so thanks to everyone who posts their problems and solutions on here.

all right, now to the newest problem. i drive a 2wd '87 with the 6.9 in it, and just lost my lift pump. drove about 1000 km (600 miles and no other choice at the time) on mainly my injection pump i believe. so i replaced the lift pump and she runs great, except i lost a lot of power (thinking i over strained the ip). now with the pedal pretty much floored i go 110km (65 mph, 4.10 gearing) and i get there very slowly.

anyways, i have a spare on a '88 7.3 and wondering if i could swap them, if this is my problem that is. any ideas give my a shout guys, thanks

 

[dyoung14]

yes a 7.3 IP will work on a 6.9,

 

[Jake S.]

Also have you replaced your fuel filter? If not, try that first.

 

[Full Monte]

When you replaced your lift pump, did you put the pump arm on the correct side of the cam? I understand that you can screw up the installation if you don't put the engine at TDC on #1. Check my facts on this as I'm speaking from a rather foggy memory on this. I'm sure someone else will remember.

 

[TWeatherford]

Yes definitely check out your fuel filter. Sounds like it is plugged. Also, I don't think that you could drive your truck at all without a working lift pump, probably couldn't even idle it.

 

[Dieselguy123]

They will run without a lift pump, as long as the fuel prime is there I Think the IP makes just enough vacuum to keep the truck running, I drove mine for a day or two with a failed electric pump and didnt even know it??

 

[Jake S.]

They will run without a lift pump, as long as the fuel prime is there I Think the IP makes just enough vacuum to keep the truck running, I drove mine for a day or two with a failed electric pump and didnt even know it??

Yep they will keep running. When my wmo was too thick(cold), I could watch through my clear return lines that the ip will pull fuel from the return line system till it finally ran out.

 

[icanfixall]

In all of the stanadyne db2 injection pumps there is a smal draw pump in the nose cone. Its not very efficiant but it will pull fuel. You wont have any hi hp or tall rpms but it will move the truck. If the fuel filter is a yaer of more old replace it but... Fill it with auto trans fluid. Run the motor for a few minutes so the atf fluid gets into the injection pump. Shut it off and let it sit overnite... Then start it and drive it like you stole it. Any gummed up or dirty injters will be cleaned up... Might even run better too. Kinda a really cheap motor tuneup that costs a quart of atf fluid.....

 

[rnh]

"When you replaced your lift pump, did you put the pump arm on the correct side of the cam?"
pretty sure i did, screwd that up once before

"Also have you replaced your fuel filter? If not, try that first."
300km on the new pump. right before this all happened i put a new filter on and filled it with diesel klean (1 week, 2000km ago), filled up both tanks with new diesel and a liter of diesel kleen each. this is my work truck that gets 80000km a year put on it, so water and sludge/algae don't have a chance to build up.
well i have a 800km trip home in a few days, so i guess i'll add a little atf to clean her up a little more and and see how it runs when it gets there. maybe a new filter there as well, easier then a ip swap. if it comes down to a swap how easy is it to time in a driveway?
thanks