It out possible to take the factory lift pump off the ip block it off, and use an electric facet pump instead?

 

Maybe: What is a facet pump?
The way the system is supposed to work is the cam driven pump supplies fuel to the inline injection pump. Fuel enters on one end of the fuel rail and has a regulator on the other end, outlet, and maintains about 18-20 PSI.
I saw a big Case wheel loader with an electric pump, the largest I have ever seen, added inline and pumping through the factory pump. It did OK for a while but the real problem surfaced. Algae from machine, storage tank and or ethanol cleaning it out. Replaced the bird catcher inline filter with a clear serviceable screen filter. Put kileem in the tank on a regular basis and serviced the filter as needed. Sorry inline filter was on the 515 IHC loader with the same problem. Case had a screen filter in sediment bowl at injection pump inlet.
I thank the factory pump is best just replace the two springs and tappet valves in them. That usually fixes them. If it has a hand pump on it probably replace it.
Some of these type systems have an inline filter that looks like a car gas filter but it is just supposed to be a screen, bird catcher before the supply pump. Then the real filter is between the supply and injection pump. Sometimes people but a gas filter there requiring it to do all the work, which it can't, and it stops up all the time. If I changed anything about the system it would be a spin on primary filter. Seems like there was another type primary screen 7'8?
That's all off the top of my head. Have not touched a 7.8 in 15 years but I thank that's all correct.
Sorry for rambling! What is your problem?

 

The problem is it's not pumping, went to fire up the motor after rebuilding it and it primed beautifully and fast, then the fuel line pulled out of the can and I reprimed it, not it doesn't seem to be pumping at all, I think the problem is just the primer but I can't find either of them I can find the lift pump with the primer for the 91 and 92 and moves an 89 I assume all that's different is where the ports for the fuel lines are. It isn't a big deal to plum it if that were the case and though I can't imagine they would really have different gph or psi I don't know for sure and I know they used a slightly different ip for those years but I can't find much information on that that, and one of the biggest things being if it will even fit. I can't give the exact specific primer for it either so I'm going to figure out the threads size and pitch on mine tomorrow and try to give one that way and get a Monark. Though if for some reason I can't find one of those yet with the correct thread or that doesn't end up being the problem then I'd just bypass it with an electric fuel pump with the same gph and psi if I can ever find the gph I need to keep that thing running, and if the pump is removed if that will effect the cam at all, on the p1700 I belive on the Cummins 5.9 they have those ports blocked off since they have a separate mechanical fuel pump but I don't know what's on the inside of the cap to just assume things. Facet is a brand of electric fuel pumps btw. I know I rambled a bit too.

 

Your local diesel fuel injection builder should be able to help you out. It is a simple deal compared to building an engine. The hand pump can allow it to suck air and loose prime. Two check valves,that's it. Never saw a piston or cylinder bad in one. No the cam won't care if you remove the pump I just thank that it's a bad idea. Maybe use a clear hose to be sure it is not sucking air.

 

Yeah I'm going to need with it more tomorrow, I just wanted to start looking around ASAP, you know, sounds like the primer really is the problem these lift pumps sound like they are built really well, thanks

 

did you ever solve this issue? How?

 

It ended up being the primer pump leaking and letting air in I replaced it with an all steel construction pump after some cross referencing with some numbers I was able to salvage off the old primer pump.

 

dang. So I replaced the plunger but it wasn’t all steel and it continued to leak the same. I hate to throw more money at the same part but maybe I got a crappy one.

 

If I remember correctly those plastic topped primers leaking were a common issue. They used the same set up on some VW diesels so people started just replacing them with the steel ones. I got a direct factory replacement directly from Bosch but never used it. The steel one has been in service for 7 years and no problems even with just sitting most of the time. Hopefully a good replacement will fix that problem. It's hard to find the actual lift pump it self.

 

fingers crossed. I ordered the one you suggested. It’s too cheap of a route to not try again.. i can find the lift pump replacement that appears identical but it’s not oem for about 250 bucks. I read that there are 2 check valves inside of it so I’m wondering if they go bad.
Just a shame I went to buy the truck it idled for well over an hour drive if a 100 miles home and bam. No prime. Thanks for the reply

 

Yeah I'd personally go with one on the higher end of the piece scale don't want to be too cheap lol. That's how it was for me kinda, the motor sat around for years outside in Pennsylvania in a scrap pile at a salvage yard, I asked about it and they gave it to me. After rebuilding it I got it running just fine, then after installing it went to prime it and nothing couldn't get it to pull any fuel.