vs v6 commodore in 1991 4 runner Fuel probs

[dawg runner]

Hi,

Got a problem with fuel lines/pressure on my v6 commo motor.

The setup i have is:

All lines using EFI hose and Clamps.
From pickup on Fuel tank through an EFI filter into VL Fuel pump.
Then from pump onto hard fuel line that pops out in the engine bay.
From there into another filter and then on to the passenger side fuel rail.
With the return on drivers side on the other hard line back to tank. which has the regulator on it.

The last hose between filter and engine keeps splitting on me????
The car has been running for a while and this has not happened to me before. For example today i turned it on for about 2 mins then off for about 5.Then when i went to start again it would struggle to start, fire and then the hose would split. This particular scenario has happened 3 times. The car is not registered so this is just me fiddling around with it in the drivevway.

Obviously it is getteng to much pressure but not sure where to start.
Could it be dirty fuel injectors/Rails??? Is the regulator cactus???
I am pretty sure the fuel pump is a bit less pressure than the VS one??? So i dont think that is the problem but i could be wrong.

Please help!!! I am soooo close to getting this bad boy on the tracks.
I have been building it for a while now.

Thanks for your help.

Cheers

DAve

[matto]

i would check you pressure reg works take the line that goes back to the tank off and put it in a bucket, start thr car and make sure the reg releases fuel if it doesnt its rooted

[dawg runner]

cheers mate. i will give that a go.

[dawg runner]

ok.

i pulled return line off in the engine bay and it is flowing fine.
it filled a 4 litre container in about a minute. now looking at the workshop manual it says the standard vs pump flows at 1.25 litres pers 30 secs meaning that the output is way to much. it is only a VL Pump and this is what i was told to use by marks adaptors.

any suggestions.

CHeers for your help.

dave

[chimpboy]

If you aren't familiar with it, it can seem a bit backwards.

It shouldn't really matter if it is flowing more fuel than you need; the whole idea is that the regulator lets out excess fuel to maintain the right pressure. This way the pump doesn't need to be a really precise item, it's the regulator that makes the system precise.

So it still sounds like you need to check the regulator.

[dawg runner]

When i had the return fuel line going back to tank the fuel line in would swell out about 5 mm when i had the return line going into bucket the line in did not swell at all. could i have a kink or serious blockage on steel return line?????

I do have a spare regulator which i will try. is it possible that the regualtor is letting too much fuel go down return line hence causing the swell in hose on the line in????

THANKS FOR YOUR HELP.

CHEERS

[chimpboy]

When i had the return fuel line going back to tank the fuel line in would swell out about 5 mm when i had the return line going into bucket the line in did not swell at all. could i have a kink or serious blockage on steel return line?????

I do have a spare regulator which i will try. is it possible that the regualtor is letting too much fuel go down return line hence causing the swell in hose on the line in????

THANKS FOR YOUR HELP.

CHEERS

I think it would be the other way round, the regulator (or the return line as you said) are not letting enough fuel leave the fuel rail so the pressure is climbing sky high. In other words it sounds like a blockage or partial blockage after the fuel rail.

[dawg runner]

changed regulator and still the same.

i think there must be a kink or blockage in the return line. NOTHING REALLY visable the rubber fuel lines are all fine no kinks and there does not appear to be any kinks in the steel line.

I MIGHT JUST BYpass the return line with some rubber hose to see if that fixes it. i guess with some careful tinkering i could get the steel line out to check it properly but it just does not make sense it has been running fine for so long.

AHHHHHHHHHHHHHHHHHHHHHHHHH!!!!

BLOODY CARS!!

[dawg runner]

could there ba a problem with running the 2nd filter so close to fuel in line???

It is about a foot from rail???

[chimpboy]

Yep, if you have some spare rubber hose run a separate fuel return line the whole way from the regulator back to the tank. Just for testing purposes not as a permanent fix.

I don't think the filter before the hose that's bursting could really be the problem. The hose must be bursting because of something blocking the lines after it.

Also, basically if it flows fine after you pulled the return line off then that tells you pretty much 100% that the problem is AFTER that return line that you disconnected.

It wouldn't have to be a kink in the line it could be a physical blockage.

With the regulator, did you try it with a regulator in place but without going the full return line? ie connect the regulator up at the engine bay end instead of the fuel tank end. That's how the regulator is set up on some cars anyway.

[dawg runner]

the regualtor on the VS is on the back of driver side rail permanently fixed.

so i think the answer to your q is yes i have tested it without going the full distance of the line. i might work my way back to tank ie there is a rubber join between steel line and tank which i might take off the tank and test flow there to see. the blockage may be in the tank itself. not likely but you never know.

thanks for your info mate just helps look out side the square. keep your info/advice coming.

cheers

[dazzah]

Hiya

I'm doing a similar thing to a navara, using vt v6, i've bought some gear from marks and bought some of the electrical stuff off v6 conversions, v6 conv tell me I have to use an EFI fuel pump...

ok just googled there site and had a look, under the 4 runner kit contents it has a EFI fuel pump listed...

Not sure if this will be your problem, but worth checking...

[mkpatrol]

When i had the return fuel line going back to tank the fuel line in would swell out about 5 mm when i had the return line going into bucket the line in did not swell at all. could i have a kink or serious blockage on steel return line?????

What sort of 4runner was it, a V6, 4 banger or a Diesel?

If it was a 4 banger, petty or diesel, the return line may be too small. the carbied petrols only had a 6mm line returning to the tank & If my memory serves me rightly the diesel was 4mm.

The Commo engine has an 8mm line returning the fuel. This may cause higher pressure that is you of control of the regulator.

There could also be a restriction in the return line in the tank.

This will be causing the swelling of the return hose while it is connected.

[dawg runner]

the return line is completely blocked.

no air going through it at all with my compressor on full ball.
Try pushing wire through but cant unblock. i have it out of the car so i will try and get one from somewhere.

cheers for your info.