fuelling issues when hot

[orange_dodo]

I got stuck in traffic yesterday and the car started spluttering and dying after sitting there for 20 minutes (it was pretty hot!). The car conked out just as I arrived at the pub but when I left a few hours later it started and ran fine.

Fuel vaporisation I though. That was until I got home and again got the same spluttering and hesitation in traffic. I was about 100m from home very jerkily travelling at 20mph when I got an almighty backfire and the engine died.

I pulled over and thought I'd prime the fuel pump a few times to draw some cold fuel into the system and get the hot stuff squirted back to the tank. Problem is the fuel pump wasn't whining. The relay was clicking but there was no whirring. I eventually managed to get the engine to run long enough to drive across the last junction and pushed the car the last 50m.

The pump definitely wasn't priming when I got it home but a couple of hours later it worked fine.

Has anyone got any suggestions as to why heat would cause the fuel pump to give up?

[GreenV8S]

It may be an electrical problem external to the pump, or an internal failure. Worth seeing if you can get it to repeat, and measure the voltage across the pump when it's working normally and when its playing up.

[s3dave]

I had similar symptoms last year, it got worse and worse. I remember on one hot day breaking down 3 or 4 times, each time after 15-20 mins it started again. I then noticed that the pump was noisy. Changed the pump and all has been ok since.

I guess it was a small vapour lock that a strong pump can overcome, but a weaker pump can’t

[orange_dodo]

Thanks for the comments guys, the only thing I have checked so far is the fuse which is fine so could be anything really. I am waiting until after the weekend to get my trolley jack and axel stands back to investigate. I don't want to be crawling under the car with only a 22yo scissor jack holding it up!

I will check the wiring and connections to make sure the fuel pump is getting all the juice it needs but if it does need a new pump how much does one cost?

[s3dave]

orange_dodo said:

but if it does need a new pump how much does one cost?

Can not remember, I got it on-line, I think it was around £60.00 - FORD Granada 2.9 Bosh 580254911

Edited by s3dave on Saturday 23 April 07:11

[Adrian@]

I would plump for pump and or wiring to the pump.
Adrian@

[orange_dodo]

Cheers, Dave

[S2Andy]

Hi, I appear to be having very similar problems with just occaissionally the car spluttering to a halt. Invariably it will restart after a period of rest. It even did this whilst idling on the ramp at the MOT test (passed!) but restarted after a few minutes
I am trying to ensure it is the pump playing up. Does anyone understand how the system operates. I have power to the pump when the key is turned, but as soon as the pump is primed / pressurised the power is cut. When running I have 12.5V at the pump. What is the mechanism for the power cut off when pressurised, so I can eliminate a sensor problem?

Thanks

Andy

[GreenV8S]

S2Andy said:

Hi, I appear to be having very similar problems with just occaissionally the car spluttering to a halt. Invariably it will restart after a period of rest. It even did this whilst idling on the ramp at the MOT test (passed!) but restarted after a few minutes
I am trying to ensure it is the pump playing up. Does anyone understand how the system operates. I have power to the pump when the key is turned, but as soon as the pump is primed / pressurised the power is cut. When running I have 12.5V at the pump. What is the mechanism for the power cut off when pressurised, so I can eliminate a sensor problem?

Thanks

Andy

Those are classic symptoms of a relay on the way out. Check all your relays are seated firmly, make sure they are all a tight fit in the contacts. If in doubt you can check for a relay dropping out by connecting a voltmeter across the contacts. (Carefully twist thin wires round the two load contacts and then reinsert the relay in its socket so you can measure it while it's installed.) If all is well, you should see zero Volts while the engine is running. If you suddenly see a Voltage here just before the problem occurs, you know this is causing the problem. If there's nothing wrong here connect your meter across the fuel pump. If the Voltage dips you know there's an electrical problem somewhere. Note that the ECU will normally switch off the fuel pump a couple of seconds after the engine dies, so you need to have the meter somewhere you can watch it while you wait for the problem to happen.

[neil240970]

Hi Tom,

No guarantee it's not the pump itself BUT it was only replaced shortly before I sold the car to you, if that helps narrow it down a bit. The wiring to the pump is massively exposed to the elements so that'd be a good place to start, I guess.

Funnily enough, I had similar issues on my way back from Cornwall yesterday just after a fill-up and a lot of uphill driving. I figured an airlock, so opened up the filler cap and turned it over and it ran fine for 250 miles from thereon. Fingers crossed..........

[GreenV8S]

neil240970 said:

it was only replaced shortly before I sold the car to you,

That begs the question: why was it replaced? Maybe this is not a new problem.

[Gerald-TVR]

Got a pump you could borrow as a test, just need postage covered

Norman

[orange_dodo]

Hi Neil,

I remembered you telling me that as that was the reason there was a spare fuel pump relay included with the car.

I have got the car up on axel stands at the moment with the rear wheel off and the pump looks nice and shiny but the wiring is very corroded. As you say Neil the wiring was a little exposed. I think my first plan will be to remove the manky connectors and replace them with another solution. In fact I have to as one of them fell apart as I disconnected it, just need to find my crimping tool.

The pump does get the full 12+ Volts when cold though which is encouraging, at least there are no large losses anywhere.

Thanks for the offer Norman, I will send you a PM if the wiring changes don't fix it. I am making the (probably stupid) assumption that the fuel pump is only ~2 years old and so is working fine.

Unless of course something in my wiring is breaking fuel pumps...

Thanks for the help everyone!

[orange_dodo]

Right well my problem had nothing to do with fueling. I replaced the connectors on the fuel pump wiring as they fell apart when I had a look at them.

The car ran fine today at a rolling road day but started stuttering on the way home. I managed to get home but as I parked up it was almost dying. I noticed a cracking sound though and when I investigated it was the coil sparking between the HT outlet and the earth.

I did a bit of waggling on the wire bundle and the car cut out completely so I think that may be the problem!

Either my coil is knackered or there is a brake in the circuit somewhere causing the coil to discharge early instead of when the distributor wants it to. That's my working theory anyway. It is supported by the fact the wire bundle I waggled was sitting on the exhaust manifold!

[GreenV8S]

orange_dodo said:

It is supported by the fact the wire bundle I waggled was sitting on the exhaust manifold!