"WARNING" High pressure pumps before IP

[clackdwack Member Find all posts View Profile Close clackdwack]

Hi all, i am running a 65Psi fuel pump to push the wvo through the system into the IP. and today on the road i saw that the fuel gauge was going down quite rapidly. after pulling the T belt cover off and i have seen that the wvo is coming out of the from seal of the IP, Like a fish drinking water. i am a diesel fitter, i know i should of known better. But does any body else run high pressure before the IP, if so be aware. i have to pull the IP off now to replace the seal. i am thinking of just putting a 10PSI pressure switch in line of the pump to shut it off once it hits 10 psi. so that it doesnt blow it again.

ANy suggestions, please.

[Guest Close David]

Re: "WARNING" High pressure pumps before IP

It has been suggested quite widely not to run high pressure feed pumps for this reason. On some cars the overflow can go into the sump which can cause lubrication problems for the engine.

To limit the fuel pressure, just use a regulator as available on evilbay or from and decent performance parts shop. $50 should get what you need complete with a gauge to calibrate the reg.

I would wonder if 10 PSI may still be on the high side? As long as the Veg is under enough pressure to not starve the OEM pump at full load, the pressure is probably irrelevant and I would think only a few PSI would be needed.

Another alternative could be to use a surge tank.
Feed the oil at full flow and any excess just goes back to the tank. The IP is fed from the bottom of the tank which ensures the is a reserve of fuel close by at all times and you can also loop your return back to the surge tank which may preserve a little heat while still bleeding off any air. Surge tanks will be around the same price as a regulator.

[Alga Senior Member Find all posts View Profile Close Alga]

Re: "WARNING" High pressure pumps before IP

Is there really a need for an extra pump, I'm setting my long range tank up with a 12 mm fuel and return line. I hope this is sufficient to draw the fuel through, as its not much further than from the normal tank and no lower.

[bruceT Senior Member Find all posts View Profile Close bruceT]

Re: "WARNING" High pressure pumps before IP

Clack, What vehicle do you have? Most of us running Mercedes don't need a fuel pump as the Bosch pump works great.

I was thinking the other day about applying slight air pressure to the tank if any assistance is needed. Say 1 kpa. If you have a plastic tank it would be quite feasible to run a tiny 12V air pump to do this job without damaging the IP. Would a non-return valve on the fuel return still allow fuel back into the tank I wonder? To ensure you don't blow up your tank a pressure release valve similar to a garden sprayer could be fitted.

Would this work?

[clackdwack Member Find all posts View Profile Close clackdwack]

Re: "WARNING" High pressure pumps before IP

i have a 2.4 Hilux. Im using the main tank as the Veg tank. I found on the highway, once i turn the pump off the engine starts to bog down but as soon as the pump goes back on presto. I was also thinking that the pump when turned off may be restricting the flow. i might remove it and see what happens. I have also noticed when i turn the pump off and get the revs up a bit you start to see bubbles come out of the Cav outlet hose, definatley causing a vacume.

[bruceT Senior Member Find all posts View Profile Close bruceT]

Re: "WARNING" High pressure pumps before IP

Clack, when you turn off the pump, you're causing a restriction and starving the engine. Yep, take out the pump and try it.

[objet Junior Member Find all posts View Profile Close objet]

Re: "WARNING" High pressure pumps before IP

I'm interested to see how you go as I'm going to be using a pump in my system. I was thinking less than 10psi would be OK but not sure of the exact pressure. Certainly can't afford to blow seals though.

[gonzalo Senior Member Find all posts View Profile Close gonzalo]

Re: "WARNING" High pressure pumps before IP

Hello all,

I find this thread really interesting as I am having exactly the same problem.
I fitted a Facet electric pump (8psi) to push the oil from the tank. With the pump off the car performance goes down. Switch it on and it goes ok again, until I floor it for a long time, for example during a long climb. In that case, even with the pump on the car feels weak.
Open the bonet, full throttle and I can see bubbles coming out of the pump, but absolutely none going in (I have transparent tubes there). So it is the pump itself sucking air. Replaced some pump seals (the easy ones) and things are better now, but not perfect.

My conclussion is that the pump will suck air no matter what unless you feed it with pressurized oil. Otherwise it seems that it is easier for the pump to suck air than oil.

Clack, is your pump electric? Would you please advise make and model? Not that I want to blow my seals. I am just thinking of fitting one of those and following Davidīs advice about a surge tank or maybe simply a by-pass with a spring loaded valve.

By the way, I would like to post a document in which a guy dissasembles a VE Bosch pump to the last bit and replaces all the seals. The quality of the pictures is excellent. It really worths a look, so I would appreciate any advice on how to post it here (I tried before without luck).

Thanks!!
gonzalo

[clackdwack Member Find all posts View Profile Close clackdwack]

Re: "WARNING" High pressure pumps before IP

my pump is electric inline 12v. i tried bypassing the pump and have a joiner to isolate the pump and found now difference, the engine was still creating vacume out of the CAV, i am going to use a 10psi pressure switch, so when the system reaches that pressures it just shuts off the pump. i was speaking to a Diesel Specialist and he reckons 10 - 15 Psi is what he test his pumps on when rebuilding them. so i dont think going any higher would be a good thing. i am only going to go 10 psi. I am only running with one HE, but its been insulated with that silver foam stuff and also the filter. I tried another way, which was i (RRRRRoAR) put 15 litres of diesel to 40 litres Veg and there hasnt been a problem. So i would say also Being winter, the oil is not quiet thin enough even when heated, for it to be createing bubbles after the CAV.

[bruceT Senior Member Find all posts View Profile Close bruceT]

Re: "WARNING" High pressure pumps before IP

By the way, I would like to post a document in which a guy dissasembles a VE Bosch pump to the last bit and replaces all the seals. The quality of the pictures is excellent. It really worths a look, so I would appreciate any advice on how to post it here (I tried before without luck).

Thanks!!
gonzalo

Gonzalo

Is the document already on the web? If so you could just provide the link as it is not possible to post the document here. The photos would not display.

Do you have web space to host the file/s? If not, I am prepared to upload the documents to my server and provide the link here.

PM me and let me know...

[gonzalo Senior Member Find all posts View Profile Close gonzalo]

Re: "WARNING" High pressure pumps before IP

Gonzalo

Is the document already on the web? If so you could just provide the link as it is not possible to post the document here. The photos would not display.

Do you have web space to host the file/s? If not, I am prepared to upload the documents to my server and provide the link here.

PM me and let me know...

Thanks Bruce.

I will show the link in another thread. You will find it in the "off topic area"

Cheers
gonzalo