Electric fuel pump wont push gas unless engine cranking?

[Jbone36]

Sick of air intrusion coming and going trying to hook up facet pump.
Ive heard people say in message board you can hook up electric and pump fuel while waiting on glow plugs to cylcle. Well unless im not cranking engine fuel wont move.what am i missing here?

 

[franklin2]

Where do you have the power wire for the pumped hooked to? Which color wire or which circuit? I hooked my pump to the old heater wire that went to the fuel filter.

 

[Jbone36]

Im holding it to positive and negative of battery..when i unhook the outlet off of injector pump it pumps plenty of fuel but hooking it up to injector pump inlet it stops because of vacume? Only lets fuel in when cranking engine.

 

[IDIBRONCO]

My guess would be that it's not vacuum related but pressure related instead. I would guess that the electric pump pumps fuel until it reaches it's maximum PSI rating. When the injector pump isn't moving internally, there's no where else for the fuel to go to so the electric pump quits pumping. Then when you start using the starter, the injector pump starts moving internally so your electric pump starts to pump fuel again. Even if there's air in the fuel system between your two pumps, it will still build enough pressure to reach the maximum rating of the electric pump.
I'm also guessing that you're confusing air intrusion with fuel drain back and mixing up the band aid solution of using the electric pump to prime the fuel system.

 

[Jbone36]

So how does everyone hook up an electric pump to solve air intrusion if it does exactly the same thing as mechanical?

 

[Jbone36]

BTW that what i meant pressure not vac..but like im saying if there is too much pressure to move fuel to injectors then whats the point of people saying to cylcle pump before glow plugs solves air intrusion hard start,?

 

[gandalf]

You cannot pump fuel through the injector pump if it is not turning. You can fill the filter and the line up to the IP, but you cannot pump fuel through the IP to the injectors. That being said, if the engine is cranking, the IP should be turning if it is working properly.

When you installed the electric fuel pump did you remove the stock lift pump? If not, did you plumb a fuel line around the lift pump or did you set it up to pump fuel through the lift pump?

 

[Cubey]

If you have your fuel filter tied into the return line system like it normally is from the factory (at least it is on both of my 6.9's), fuel will be pumped into the return line system, which can help with air purging. Plus it'll be at pressure when you start cranking, unlike the mechanical pump that has to build up pressure when the engine begins to crank over.

 

[IDIBRONCO]

whats the point of people saying to cylcle pump before glow plugs solves air intrusion hard start,?

That's not air intrusion. It's fuel drain back. They can be related, but are two different , separate problems. Air intrusion only happens when the engine is running and drawing air into the fuel system. It can only happen before the injector pump. One possible cause of fuel drain back is if the one way valve in the mechanical lift pump fails. You can install an aftermarket one way valve in the rubber line before the mechanical lift pump to see if this helps.

 

[The_Josh_Bear]

Yep as said above the fuel filter is getting purged of air, which is where the fuel drain-back affects our systems.
The good thing about the IP being a dead head when off means it's not losing it's prime. Just the fuel filter and if you have the line to the return system intact all the air will blow out of that right away and not into the IP once it starts turning.
Also very good point about fuel drain-back vs air intrusion by @IDIBRONCO. They are often confused but are definitely not caused by the same issue.

 

[MtnHaul]

going trying to hook up facet pump.

With all the people who've had unsatisfactory performance with the Facet lift pump, which I am assuming you're using, why are you going that route? Yeah I still have one on my truck but that's only 'cuz I've been getting over back surgery for the last year and a half so fixing things that aren't quite broke was a low priority. I have the 9-11psi model and it won't pump enough fuel to maintain a hard pull uphill in 2nd or 3rd at high RPMs--fuel filter light comes on. Just my .02

 

[IDIBRONCO]

With all the people who've had unsatisfactory performance with the Facet lift pump, which I am assuming you're using, why are you going that route?

Yes he did say that he installed a Facet. My guess is that he's just using it to try to overcome the fuel drain back issues and not run the engine (I hope).

 

[franklin2]

I think he is confused to how the injection system works. The electric pump you are messing with is called the "lift pump". It's only job is to supply fuel to the injection pump at about 5 psi or so. It's the injection pump's job to pump fuel to the injectors at around 1800 psi. This is purely mechanical and depends on the engine turning to operate.

A electric lift pump will "help" a air intrusion problem, but it will not fix a air intrusion problem caused by a leaky fuel system. If you have a fuel system full of air, it will take a very long time for the little pump to purge all the air out of the system and its not going to get all the air out. Only repairing the leaks will completely solve your problem.

 

[NeverHave-I-Ether]

Fuel drain back is a popular issue for the electric pump conversions. Adding a check valve is the way to go, eh?

 

[IDIBRONCO]

Adding a check valve is the way to go, eh?

I won't say yes. It depends on where exactly your fuel is draining back from. It sure won't hurt though. It didn't help me, but I have a seal on the IP that leaks when it gets cold so it's not exactly fuel drain back in my case either. It's just the IP draining.