elise S1 fuel pump problems
Discussion
hi guys,
I've got an issue with my elise (1997 standard car), while driving it to work the other week it just cut out, like not having any fuel in it left. Got it back home after I called a friend who brought fuel and subsequently a towing rope.
After reading similar posts on pistonheads on fuel pump/immob/leccy issues at this point I'm completely blank.
Here's the situation, I've replaced the MFRU, bypassed the cobra system, (and by the way there is a spark!!) took out the fuel filter (which was full of dirt) to see if there's fuel flowing and there wasn't...
I took the fuel tank out too see if the pump was broken, it isn't, when i put it on a battery its fine. Started checking the circuits, at the fuel pump connector when i put ignition on there is 12V for a second then it dies, when I crank it its back to 12V continuously. At the fuel pump fuse its fine, 12V at both ends.
So... issue between the fuse and the pump where something is shutting down the circuit.
Has anyone got experience with these kind of issues, any ideas will be greatly appreciated!
thanks
I've got an issue with my elise (1997 standard car), while driving it to work the other week it just cut out, like not having any fuel in it left. Got it back home after I called a friend who brought fuel and subsequently a towing rope.
After reading similar posts on pistonheads on fuel pump/immob/leccy issues at this point I'm completely blank.
Here's the situation, I've replaced the MFRU, bypassed the cobra system, (and by the way there is a spark!!) took out the fuel filter (which was full of dirt) to see if there's fuel flowing and there wasn't...
I took the fuel tank out too see if the pump was broken, it isn't, when i put it on a battery its fine. Started checking the circuits, at the fuel pump connector when i put ignition on there is 12V for a second then it dies, when I crank it its back to 12V continuously. At the fuel pump fuse its fine, 12V at both ends.
So... issue between the fuse and the pump where something is shutting down the circuit.
Has anyone got experience with these kind of issues, any ideas will be greatly appreciated!
thanks
i've cleaned and reconnected two earth points, one which is near the inertia switch and the other is the one that you see from below underneath the car, on the gearbox side (its on the chassis with this stupid insert bush)
Im looking into the service manual now to see if there's a wiring diagram for the fuel pump.
Im looking into the service manual now to see if there's a wiring diagram for the fuel pump.
Thats what I'll be doing next, really thoroughly checking all the wiring and connectors, double-checking the inertia switch (about the only cheap component i haven't replaced already). I really hope its not an ECU fault, I might try and swap it out with one from my friends elise, maybe that will shed more light on the mystery.
Busy times this week so have to wait till next weekend for any results.
Thanks for your help scuffers!
Busy times this week so have to wait till next weekend for any results.
Thanks for your help scuffers!
I was thinking today... maybe its possible to read the ECU data for any fault codes that appear using the OBD plug.
I have a feeling that it IS going to turn out to be the ECU thats causing this whole mess.
Are there replacement units available? (I won't be buying one until I am 100% certain its engine management of course)
I have a feeling that it IS going to turn out to be the ECU thats causing this whole mess.
Are there replacement units available? (I won't be buying one until I am 100% certain its engine management of course)
Today I got round to looking at the car again, first thing I did was checking the circuits from the service manual. I now have a pretty good understanding of the way the whole thing is connected and powered. I took out the multimeter and I am sorry to say but haven't been able to fix bugger all...
Same situation as before fuel pump is powered for a fraction of a seconds when ignition is put on then dies. Inertia switch is OK. So its either immob or ECU or harness connectors. I've cleaned checked and reconnected the plugs and earths. When I start measuring the voltage on the circuit after the inertia switch there are really strange reading that don't add up with what I'm reading at the pump.
Same situation as before fuel pump is powered for a fraction of a seconds when ignition is put on then dies. Inertia switch is OK. So its either immob or ECU or harness connectors. I've cleaned checked and reconnected the plugs and earths. When I start measuring the voltage on the circuit after the inertia switch there are really strange reading that don't add up with what I'm reading at the pump.
Scuffers said:
you can't swap ECU's, they are coded...
just test the fuel pump cct by grounding the ECU fuel pump trigger wire...
How exactly are they "coded" don't really get that, its a 90's car! surely you can just swap the bjust test the fuel pump cct by grounding the ECU fuel pump trigger wire...
dsI haven't come across any fuel pump trigger wire in any texts I read about this, can you tell me more please scuffers...
Rudy 111 said:
Scuffers said:
you can't swap ECU's, they are coded...
just test the fuel pump cct by grounding the ECU fuel pump trigger wire...
How exactly are they "coded" don't really get that, its a 90's car! surely you can just swap the bjust test the fuel pump cct by grounding the ECU fuel pump trigger wire...
dsI haven't come across any fuel pump trigger wire in any texts I read about this, can you tell me more please scuffers...
ECU trigger for the fuel pump relay is pin 20 on the ECU, this goes to pin 1 of the small plug on the MFRU
if you ground this when the ignition is on, the fuel relay will close and the pump should run.
Here is an update..finally. I guess it turned out there were two issues, my fuel pump was not priming because of the broken cobra unit, probably, and there was a fault with the fuel pump itself.
I took at the cobra unit completely, I only have the lucas system on the car now which work perfectly.
When I took the petrol tank out it was full of rust and old paint residue on the inside, (the pump has had a very hard life in the final stages). I tested the pump on a battery and I thought it worked, as it turned out is was spinning but not pumping. I should have bloody checked the thing properly before building it back into the car with my completely refurbished fuel tank.
I ordered the new pump and the car is running again!!! very happy with that.
My elise has been off the road for three months or more, but I took the opportunity to do a lot of other work too, fuel tank, as I said, radiator, header tank and spider hose, some exhaust work and and and......
When I though it could be the Mems unit it is now clear that this was not the situation, as scuffers said...
I took at the cobra unit completely, I only have the lucas system on the car now which work perfectly.
When I took the petrol tank out it was full of rust and old paint residue on the inside, (the pump has had a very hard life in the final stages). I tested the pump on a battery and I thought it worked, as it turned out is was spinning but not pumping. I should have bloody checked the thing properly before building it back into the car with my completely refurbished fuel tank.
I ordered the new pump and the car is running again!!! very happy with that.
My elise has been off the road for three months or more, but I took the opportunity to do a lot of other work too, fuel tank, as I said, radiator, header tank and spider hose, some exhaust work and and and......
When I though it could be the Mems unit it is now clear that this was not the situation, as scuffers said...
Edited by Rudy 111 on Sunday 22 April 19:40
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