Fuel to engine problem Audi 80 Sport 84' - Page 2

missfire · 02-03-10, 11:39 PM

just process of elimination.......we'll get there in the end.

are you damn sure its starvation and not flooding...? checked the plugs..??

nickt241 · 02-03-10, 11:41 PM

check the earth for the pump,chances are it will be corroded and giving an intermittant connection,you can test this by linking in a temporary earth on the negative terminal on pump then driving car to see if symptoms persist,while you are there make sure both positive and negative terminals on pump are secure...if this dosent sort it then change the relay(easy and cheap)also check connections on plug to relay and give them a blast of WD,relays can break down over time as they only contain a wire coil and a set of duel points similar to ignition points........if neither of these virtually free repairs cure it then it will be the pump cos theres nothing left....its doubtful to be tank debris but even if it is then it renders the pump U/S

Hanuman · 02-03-10, 11:42 PM

I got the impression that this was happening infrequently. But with it happening so quickly, I'm inclined to think that the fuel pump is a likely culprit.

But. I'm not a fan of replacing things until some work has been done to identify exactly whats happening.

as mentioned earlier

-4ltr/min roughly, checked at the return line.
-5bar pressure minimum, with the system connected normally
-5-8 amps running current, and the pump really does need 12v to work well (there is a relay mod which has been carried out on ur's a lot)
-Fuel pump relays can be at issue, occasionally. Bridging the relay contacts so the pump runs continuously is worth a go. ONLY for test purposes, to identify the problem. If that works, then a new relay. Don't be tempted to run that permanently.
-check the filters again, see if they are full of crap, again. How much did you remove last time?

80sport_owner · 02-03-10, 11:46 PM

Quote:

Originally Posted by Coxy

If the noise gets louder before it's about to stall, it could be a fuel blockage before the pump.

Sounds like something is restricting the fuel flow which is causing the pump to do that.

Yeah, cheers coxy. Any tips on trying to check/clear blockage from tank?

See because i was wondering if all the audi's of that era had 2 fuel pumps. Wasn't sure if the previous owner had put an electric one on and there was some kind of fight between the electronic and the mechanical pump. But the answer is probably bits of rust in the tank.

missfire · 02-03-10, 11:51 PM

Quote:

Any tips on trying to check/clear blockage from tank?

tank out job on mine.............t'was fun....!

..where is the pump...is it 'in tank' ....''wet pump''...??

80sport_owner · 02-03-10, 11:54 PM

Quote:

Originally Posted by nickt241

check the earth for the pump,chances are it will be corroded and giving an intermittant connection,you can test this by linking in a temporary earth on the negative terminal on pump then driving car to see if symptoms persist,while you are there make sure both positive and negative terminals on pump are secure...if this dosent sort it then change the relay(easy and cheap)also check connections on plug to relay and give them a blast of WD,relays can break down over time as they only contain a wire coil and a set of duel points similar to ignition points........if neither of these virtually free repairs cure it then it will be the pump cos theres nothing left....its doubtful to be tank debris but even if it is then it renders the pump U/S

Cheers, I have lifted rear seat to check the earth which seemed fine. (took it off and scratched at it for good measure)
As for the relay, it sounds normal to me as if its doing its job. Do you know why the relay clicks twice if the ignition is turned half (engine not on) But on full ignition it only 'clicks' once. Is this normal? It basically gives two bursts of fuel on half key turn but only one on full ignition.

80sport_owner · 03-03-10, 12:02 AM

Quote:

Originally Posted by missfire

tank out job on mine.............t'was fun....!

..where is the pump...is it 'in tank' ....''wet pump''...??

Not a wet pump, unless there another one of the bastards that i dont know about. Its all just a bit strange. I changed the fuel filter and petrol was pissing free from the tank non stop so then makes me wonder what else it could be. Its going to be a trail and error situation i think. Ill start with the cheap options like taking cap off, then check line pressure; last option taking the f'ing tank out

Think a fuel pump will have to be in order perhaps.

Hanuman · 03-03-10, 12:04 AM

Quote:

Originally Posted by 80sport_owner

Its going to be a trail and error situation i think.

It needn't be. I know it's your daily machine, but some time and considered action will pay dividends.

80sport_owner · 03-03-10, 12:10 AM

Quote:

Originally Posted by Mark Hanman

It needn't be. I know it's your daily machine, but some time and considered action will pay dividends.

Yeah I welcome myself to classic car motoring

I knew it wasn't going to be plain sailing - wheres the fun in that ay?

But thanks for all the help! I'm no mechanic but always up for learning, the hard way perhaps.

nickt241 · 03-03-10, 01:01 AM

when the pump is first powered up(2nd turn on key i expect)it will fuel up to pressure then turn off until the pressure drops,ie it starts,when you switch to ignition the pump is already up to pressure so wont need any more than one pump,i expect if you sit in car with ign on but engine not running youll find that the pump clicks every 30 seconds or so to maintain fuel pressure......change the relay,or just temporarily swop it with a headlight one to test,make sure the relay you use has the same amount of terminals and make sure it aint an indicator or hazard light relay.......you can bridge the terminals to test as the guy said before but im geussing that your probrably not proficient in electrics so your better off just swopping relays as you cant cause any damage doing this ok

02-03-10, 11:42 PM	#13
Hanuman Trickster Classic Audi Club Member Join Date: May 2009 Location: Heckling from the cheap seats, Phnom Penh, KoW Posts: 7,016	I got the impression that this was happening infrequently. But with it happening so quickly, I'm inclined to think that the fuel pump is a likely culprit. But. I'm not a fan of replacing things until some work has been done to identify exactly whats happening. as mentioned earlier -4ltr/min roughly, checked at the return line. -5bar pressure minimum, with the system connected normally -5-8 amps running current, and the pump really does need 12v to work well (there is a relay mod which has been carried out on ur's a lot) -Fuel pump relays can be at issue, occasionally. Bridging the relay contacts so the pump runs continuously is worth a go. ONLY for test purposes, to identify the problem. If that works, then a new relay. Don't be tempted to run that permanently. -check the filters again, see if they are full of crap, again. How much did you remove last time? __________________ I wish they would keep the damned Chinese away now that I can go home, so that I can enjoy Fish amok and a draught Angkor

02-03-10, 11:39 PM	#11
missfire making wooden things Classic Audi Club Member Join Date: Dec 2009 Location: cow land Posts: 8,156	just process of elimination.......we'll get there in the end. are you damn sure its starvation and not flooding...? checked the plugs..??

02-03-10, 11:41 PM	#12
nickt241 Grown up member Join Date: Feb 2010 Posts: 132	check the earth for the pump,chances are it will be corroded and giving an intermittant connection,you can test this by linking in a temporary earth on the negative terminal on pump then driving car to see if symptoms persist,while you are there make sure both positive and negative terminals on pump are secure...if this dosent sort it then change the relay(easy and cheap)also check connections on plug to relay and give them a blast of WD,relays can break down over time as they only contain a wire coil and a set of duel points similar to ignition points........if neither of these virtually free repairs cure it then it will be the pump cos theres nothing left....its doubtful to be tank debris but even if it is then it renders the pump U/S

03-03-10, 01:01 AM	#20
nickt241 Grown up member Join Date: Feb 2010 Posts: 132	when the pump is first powered up(2nd turn on key i expect)it will fuel up to pressure then turn off until the pressure drops,ie it starts,when you switch to ignition the pump is already up to pressure so wont need any more than one pump,i expect if you sit in car with ign on but engine not running youll find that the pump clicks every 30 seconds or so to maintain fuel pressure......change the relay,or just temporarily swop it with a headlight one to test,make sure the relay you use has the same amount of terminals and make sure it aint an indicator or hazard light relay.......you can bridge the terminals to test as the guy said before but im geussing that your probrably not proficient in electrics so your better off just swopping relays as you cant cause any damage doing this ok