Gauges and fuel pump
#1
08-17-2011, 12:32 AM
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Gauges and fuel pump
Hi all,
I just replaced the lower control arm (among a lot of other things). 1987 XJ-S V12 5.3L. Major PITA, since I did it all by myself! The car ran well before, but now I have 2 issues. The fuel pump seems to work fine while cold, but after about 15 minutes, it dies. If I wait 15-20 minutes, it will start and run fine, again. I replaced the fuel filter - it was pretty bad - no change.
The other issue is that none of my gauges work, except the speedo and tach. Most simply don't do anything, but the fuel gage pegs with the ignition on.
I noticed that when I dropped the front suspension, I forgot to disconnect the ground wire from the sub-frame to the chassis. I reconnected it, but no change.
Any ideas/insights would be particularly welcome!
Thanks and best regards,
Ron
I just replaced the lower control arm (among a lot of other things). 1987 XJ-S V12 5.3L. Major PITA, since I did it all by myself! The car ran well before, but now I have 2 issues. The fuel pump seems to work fine while cold, but after about 15 minutes, it dies. If I wait 15-20 minutes, it will start and run fine, again. I replaced the fuel filter - it was pretty bad - no change.
The other issue is that none of my gauges work, except the speedo and tach. Most simply don't do anything, but the fuel gage pegs with the ignition on.
I noticed that when I dropped the front suspension, I forgot to disconnect the ground wire from the sub-frame to the chassis. I reconnected it, but no change.
Any ideas/insights would be particularly welcome!
Thanks and best regards,
Ron
#2
08-17-2011, 05:26 AM
Ron,
Couple of things come to mind.
When the car was jacked and supported to the small job, did by chance, something crush the fuel supply pipe (right side) or the fuel return pipe (left side), maybe the jack stands. Have a look see under the car and make sure thay are not crushed, as I have seen many like that after a simple tyre change at a tyre shop, mine was one of them, coz they simply refuse to jack the car using the jacking points??.
The earth strap is my next thought. Did they get put back right. Engine to subframe, then subframe to chassis, Or, as I have done, engine to chassis direct, one on each side. Then one from the alternator casing to chassis just because. I dont use Jaguar cables, just some generic battery cables with eyelets at each end. Make a real effort on these, and make real sure that the contact areas are REAL CLEAN.
The gauges etc are all kind of linked to the earth system in some way. The speedo and tacho are earthed at the binnacle, as is the volt meter, and fuel gauge, so that pegging is a mystery at the moment.
Since the fuel filter was "pretty bad" and since it is AFTER the pump, the pump has had some gunge going through it, and has probably just gone legs up, it does happen sometimes.
The fuel pump relay (in the boot plugged into the "black" socket) may also be getting tired.
Being an '87 the ECU should be a 16CU, which is NOT known to have fuel pump circuit issues like its predessor, so the relay is my bet after the pump.
Couple of things come to mind.
When the car was jacked and supported to the small job, did by chance, something crush the fuel supply pipe (right side) or the fuel return pipe (left side), maybe the jack stands. Have a look see under the car and make sure thay are not crushed, as I have seen many like that after a simple tyre change at a tyre shop, mine was one of them, coz they simply refuse to jack the car using the jacking points??.
The earth strap is my next thought. Did they get put back right. Engine to subframe, then subframe to chassis, Or, as I have done, engine to chassis direct, one on each side. Then one from the alternator casing to chassis just because. I dont use Jaguar cables, just some generic battery cables with eyelets at each end. Make a real effort on these, and make real sure that the contact areas are REAL CLEAN.
The gauges etc are all kind of linked to the earth system in some way. The speedo and tacho are earthed at the binnacle, as is the volt meter, and fuel gauge, so that pegging is a mystery at the moment.
Since the fuel filter was "pretty bad" and since it is AFTER the pump, the pump has had some gunge going through it, and has probably just gone legs up, it does happen sometimes.
The fuel pump relay (in the boot plugged into the "black" socket) may also be getting tired.
Being an '87 the ECU should be a 16CU, which is NOT known to have fuel pump circuit issues like its predessor, so the relay is my bet after the pump.
#3
08-17-2011, 05:36 AM
#4
08-17-2011, 10:51 AM
Join Date: Aug 2011
Location: Pope Valley, CA
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Thanks Grant - notes in blue below!
I really appreciate your reply, and will post my findings!
Ron
Ron,
Couple of things come to mind.
When the car was jacked and supported to the small job, did by chance, something crush the fuel supply pipe (right side) or the fuel return pipe (left side), maybe the jack stands. Have a look see under the car and make sure thay are not crushed, as I have seen many like that after a simple tyre change at a tyre shop, mine was one of them, coz they simply refuse to jack the car using the jacking points??.
Hehe - "small job" - had to drop the whole subframe just to change the lower control arm! I just checked, and the fuel lines appear to be ok.
The earth strap is my next thought. Did they get put back right. Engine to subframe, then subframe to chassis, Or, as I have done, engine to chassis direct, one on each side. Then one from the alternator casing to chassis just because. I dont use Jaguar cables, just some generic battery cables with eyelets at each end. Make a real effort on these, and make real sure that the contact areas are REAL CLEAN.
Actually, I didn't have the earth strap to the chassis connected. Put it back, but no change.
The gauges etc are all kind of linked to the earth system in some way. The speedo and tacho are earthed at the binnacle, as is the volt meter, and fuel gauge, so that pegging is a mystery at the moment.
I'm starting think it may be the ground inside the panel - I'll remove and check, today - keeping fingers crossed!
Since the fuel filter was "pretty bad" and since it is AFTER the pump, the pump has had some gunge going through it, and has probably just gone legs up, it does happen sometimes.
Since I have another parts car, I'll try swapping the pumps.
The fuel pump relay (in the boot plugged into the "black" socket) may also be getting tired.
I tried a new relay with the same results.
Being an '87 the ECU should be a 16CU, which is NOT known to have fuel pump circuit issues like its predessor, so the relay is my bet after the pump.
It does have the 16CU, which was replaced a few years back. Glad it shouldn't be the problem!
Couple of things come to mind.
When the car was jacked and supported to the small job, did by chance, something crush the fuel supply pipe (right side) or the fuel return pipe (left side), maybe the jack stands. Have a look see under the car and make sure thay are not crushed, as I have seen many like that after a simple tyre change at a tyre shop, mine was one of them, coz they simply refuse to jack the car using the jacking points??.
Hehe - "small job" - had to drop the whole subframe just to change the lower control arm! I just checked, and the fuel lines appear to be ok.
The earth strap is my next thought. Did they get put back right. Engine to subframe, then subframe to chassis, Or, as I have done, engine to chassis direct, one on each side. Then one from the alternator casing to chassis just because. I dont use Jaguar cables, just some generic battery cables with eyelets at each end. Make a real effort on these, and make real sure that the contact areas are REAL CLEAN.
Actually, I didn't have the earth strap to the chassis connected. Put it back, but no change.
The gauges etc are all kind of linked to the earth system in some way. The speedo and tacho are earthed at the binnacle, as is the volt meter, and fuel gauge, so that pegging is a mystery at the moment.
I'm starting think it may be the ground inside the panel - I'll remove and check, today - keeping fingers crossed!
Since the fuel filter was "pretty bad" and since it is AFTER the pump, the pump has had some gunge going through it, and has probably just gone legs up, it does happen sometimes.
Since I have another parts car, I'll try swapping the pumps.
The fuel pump relay (in the boot plugged into the "black" socket) may also be getting tired.
I tried a new relay with the same results.
Being an '87 the ECU should be a 16CU, which is NOT known to have fuel pump circuit issues like its predessor, so the relay is my bet after the pump.
It does have the 16CU, which was replaced a few years back. Glad it shouldn't be the problem!
Ron
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