Lift pump...If...and what if....

[weejimmy]

why not route a return pipe into the car through the window etc into a big clear bottle to see if you are still returning fule under high load, then you know if you are geting enough fule to the pump or not, so you know if you need to bother about a lift pump or not.

[darrenjlobb]

Because the pump will still return fuel, even if its not getting enough... its just the internal pressures drops....

[Rabbit on Roids]

So having a smaller tank in the engine bay, which the lift pump just sends / returns to, and the injector pump sends / returns to would be a better idea?

Or doing the inlet / oulet pipe...i guess that would work...altho would the fuel not find ti easier to go this way than to the pump / starve the pump just the same,...

its not necessary to have 2 tanks, you are overthinking, and overcomplicating things. i would just hook up a few psi feed directly to the pump inlet. its worked fine for those of us that have done it.

[Rabbit on Roids]

Or doing the inlet / oulet pipe...i guess that would work...altho would the fuel not find ti easier to go this way than to the pump / starve the pump just the same,...

I assume this is in regard to what I last posted.  If a higher than 5-psi pump is used, then the whole point is to alleviate the higher pressure so that it doesn't mess up the dynamic advance.  The point is to eliminate both pressure or vacuum at the pump inlet and let the injection pump will draw it's own fuel which it has no trouble doing unless there is a fuel restriction or the pump is severely worn.  There is no way that alleviating excessive inlet pressure in the described manner would starve the pump unless the vane pump didn't function at all.  In which case, your dynamic timing advance would not function at all, your power would be off and your fuel economy would be terrible.  Under that condition you'd want to replace the pump anyway.   

that was clear as mud.

so are you saying that its fine to run a lift pump, or are you saying not to run one?

[darrenjlobb]

Right this was  my plan...basically im just trying to allow the pump to have fuel right there ready for it, so it dosnt have to drag it so far, i am thiniking to just t across the lines with a one way valve, because the pump can easily suck what it needs then...

[burn_your_money]

The only issue that I can see with teeing across the pump is that there may end up being too much pressure on the return side and the injector return lines may start leaking.

[darrenjlobb]

I can see your point here yes....would have to try it i suppose...if i had to i suppose i could run the t;ed pipe back a dedicated return...

[Smokey Eddy]

There is a seller on ebay who sells solid state fuel pumps that are diesel safe.
just search "solid state fuel pump"
and there are a few with different pressure ranges. I've wanted to get one for a while i just need to justify spending more money on the car first.

[monomer]

CIS pumps run hot. When I had my Mercedes with a cis system, pump pressures would reach beyond 90PSI. I would be careful with that.


I have a walbro FPR-15 lift pump made for this application, It ran me about $90 and is biodiesel ready. It's outlined elsewhere on this forum.

[AudiVWguy]

You guys need to listen to what Andrew said. Use a by-pass and check valve. I tried a Facet pump for a while, Its about 4 psi, Hooked it up with the pump return pressure gauge installed. It will change the timing curve. I didn't like it.

[Rabbit on Roids]

you guys are sure that 3 psi is going to affect timing that much? dont our pumps have almost 100psi in them at 3k rpms? how is 3 psi going to negatively affect timing that much? dont we all try and advance our timing anyway? im just not getting it so good. my car ran WAY BETTER when i added a lift pump.

[Powered by Spearco]

Question,
I'm using a Facet lift pump inline to a Giles pump. My engine makes a noise such as if the timming is wrong at idle, and smokes, but when loaded, the noise seems to deminish. At least that what it sounds like.
Is this due to the lift pump. I guess the only way to tell is to remove it and check.

[Rabbit on Roids]

how many psi are you running at the pump inlet? the way andrew described it, that would sound about right, building some excessive pressure on the inlet side of the pump, and then its retarding the timing.

[Powered by Spearco]

What ever the psi rating of the pump plus the location.

[sdwarf36]

I've had a small Facet pump mounted between the filter + Ip for the last 60k miles. When I 1st put it on, I ended up blowing the small return lines off the injectors. I then put a CR press. regulator and gauge on-set it around 3 psi-haven't had a problem since.