1.8L CIS K-Jetronic injection problems

[Anonymous]

Thought I'd consult the brains trust before committing to a new fuel pump. What do you guys make of these sypmtoms? This I've worked out so far.

1 something causes the fuel pump to draw a lot of current and blow it's fuse.

2 sometimes it rights itself and a new fuse (15A) gets it going.

3 Sometimes it doesn't! You can hear the pump trying to spin but it seems stuck and draws a heap of current in this state. Nearly burnt out the wiring proving this.

Here's what I've checked.
1 Wiring loom to pump for shorts along the run.
2 Removed and bench tested (dry run) the pump, seems fine perhaps noisy.
3 checked fuel accumulator (next in line gadget from pump) seems fine, not blocked.
4 Replaced fuel filter, old one seemed restrictive and well past use by date in any case.
5 blown out fuel line to engine bay.

Questions
Could this be caused by something other than the pump itself? If the fuel distributor was not returning fuel to the tank properly would the pump stall or just spin away merrily? If so what would be the other symptoms of the regulator blocking up? Wouldn't that cause too much fuel pressure at the injectors and some pretty eratic running?

The car runs fine when the pump is working.

I've had these pumps fail in my Porsche 924s but the symptoms were different they'd just stick and a light tap would get them started.

Engine prefix GX
1800 K-jetronic CIS and electronic ignition.
Fuel pump 0580 254 980

Thoughts?
Comments?
Wisdom?

Thanks in advance
Pete Jones

[Peter Jones]

I was sure I was logged in when I typed all that out. Doh!

Pete Jones

[syncro]

Re: 1.8L CIS K-Jetronic injection problems

Questions
Could this be caused by something other than the pump itself? If the fuel distributor was not returning fuel to the tank properly would the pump stall or just spin away merrily? If so what would be the other symptoms of the regulator blocking up?

Sounds like there could be a restriction at the fuel distributor end. I think that there is strainer hidden in there somewhere.

[20v kit car]

Just as phil suggested there is astrainer near the fuel dist head...remove and throw to the shi house..its located in the line coming in..like two screw fitting .....good idea to check at the fuel tank pickup end..have seen forgien materials cause restricted pickup..good luck be careful of dry running pumps for too long as they are fuel cooled and lubricated..cheers steve

[roccodingo]

If you have a remote pump switch, disconnect the fuel line at the fuel filter inlet, activate the pump briefly and see if there is heaps of fuel flowing. be prepared for juice going everywhere tho...then move along the fuel path till you find the point of restriction...

[Peter Jones]

Thanks Grant I'll try that. I'm pretty sure every things ok up to the fuel distributor but perhaps the return path is blocked. I'll get back to you all after the weekend, I don't get much of a chance during he week to get out to the garage much.

Thanks for the input
Pete Jones

[Roscoe]

If it is drawing that much current I would say it has had it, even with the fuel return blocked off completely I wouldn't expect that. If the pump is noisy in the car it could be that you have a lift pump in the tank that is not working. Not sure what car you have? That will put excess load on the pump as it tries to draw fuel from the tank.

[syncro]

Not all of them have lift pumps.
It may be sucking a bit of air also.

[Peter Jones]

No lift pump. The car's a '79 GLD Mk1 with the original diesel tank. The motor is an 1800 8V K-Jetronic. GX prefix (1985-1988 Golf Jetta?????). Yeah I would have thought that with the fuel line blocked off it would still spin and just sit there cavitating and not draw much more than usual. Just want to make sure I'm not barking up the wrong tree!

Pete

[syncro]

Yeah I would have thought that with the fuel line blocked off it would still spin and just sit there cavitating and not draw much more than usual. Just want to make sure I'm not barking up the wrong tree!

Pete

If it cavitates it will overheat as the fuel is also for cooling.

[Anonymous]

syncro is right, but it won't necessarily cavitate if the pressure is too high. If a new pump is noisy in the car it can be a sign of cavitation hence my earlier comment on the lift pump. If the pump cavitates it will not last very long. I am not familiar with the diesel fuel tank in a Mk1 but it is important that the roller cell pump is gravity fed with fuel and not trying to suck fuel from the top of the tank as it would in a Mk1 carburettor tank. The pump is not designed to suck fuel which is why a lift pump is used in some installations where it is not possible to draw fuel from the bottom of the tank. The diameter of the fuel feed pipe from the tank to the pump is important too and there should be a pre filter (100 micron) fitted between the tank and the pump.

[Roscoe]

oops, thought I had signed in. that last post was mine.

[Peter Jones]

The Fuel Line from the tank to the pump is a 13mm. The pump sits beside the tank and is lower than the pipe coming out of the tank. There's no filter between the tank and the pump. There didn't seem to any problems gravity feeding fuel from the trank to the pump it certainly flowed out on the garaqge floor quick enough when the vice grips came off the fuel line! More investigation required.

Pete

[sydneymk1]

pump drawing to much current

u say its noisy and draws to much current.
this is an old pump right?
sounds like its polling- this means internal bearings worn out and the spinning part of the motor catches on the stationary part
where u from i could lend u a spare benz one just to test it out

[Peter Jones]

Yep, I've pretty much come to that conclusion. Thanks for the offer of a loaner, but I've got a brand new one on the way. I'll let you all know how it works out!

Pete Jones