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Fuel pump relay clicking when restarting engine when warm/hot

302 Views 10 Replies 3 Participants Last post by  UcatchMyDrift?
Hi, wondering if anyone has any thoughts on this problem..

No problems (yet) when the engine is cold.

If i go for a long enough drive (say 10 miles+) allowing the engine to get pretty warm, not crazy hot though, i then stop the engine, start it again say 10 mins later, most of the time now, the fuel pump relay will start clicking on cranking, or a minute or two after starting. This makes the car undriveable for obvious reasons whilst it is happening. Give it 10mins or so to cool down, and alls fine again.
Last year i first noticed it after getting pretty hot/long drives etc then as above.
Didnt happen for most of the winter due to lower temps outside.
Seems to be happening easier this year though, so getting worse i think.

If i get the engine nice and hot, i can switch off, ( starting up again straight away gives no issues) give it 10 mins, go to start, and the fuel relay will not even click on, resulting in the engine not firing at all, give it 10-20mins to cool down, and all good again.

Seems like some kind of heat soak to me? I did get the tuner to switch on a safety feature in the ms3 mini that cuts fuel when a lean condition is detected, and i was sure that must have been the cause due to heat soak, leaning out the fuel due to the iat getting hot, then the ms3 picking that up as a lean condition and cutting power to the fuel pump relay, but my theory seems wrong as i switched it off yesterday, and it happened again today 馃檮.

The car is a 2000 mk2, ms3 mini, td04.

I modified everything myself accept for doing the tuning. I have been meticulous with everything in the build. Any wiring that i have done has been done very thoroughly, sleaved, soldered, stress relief etc (i build wiring harnesses for a living). The car is in very good condition for its age, the rest of the wiring is good that i can see, any earths that i have found have been replaced.

Failing sensor causing ms3 to cut fuel? Pretty sure the only sensors left that havent been changed are cam angle and crank?

Going to check under the footwell where the ms3 is and give it all a good wiggle, but cant think that would be the cause due to the heat issue causing it?

Thanks 馃憤馃憤馃槂馃槂馃槂

(oh, and, last year i got another (second hand) fuel relay, and no difference)
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pop your main relay out in the engine bay and check the plastic around both the connector in the car and the relay itself
pop your main relay out in the engine bay and check the plastic around both the connector in the car and the relay itself
Thanks, will do 馃憤. (pretty sure i had a look at it last year, as, if i remember its located next to the fuel relay, but ill definitely check it again.)
Its either the crank or the cam sensor. This is very common on the Mk2/Mk2.5 engines. You will also notice that the tachometer gauge bounces when it happens. You can get a composite log when it happens and it will show whether its the crank or the cam.
Its either the crank or the cam sensor. This is very common on the Mk2/Mk2.5 engines. You will also notice that the tachometer gauge bounces when it happens. You can get a composite log when it happens and it will show whether its the crank or the cam.
Thanks reverant, i havent noticed the tach guage bouncing, but i may well have not noticed if it only bounces a little.. Ill have a look into how to do the composite log, as ive not done any data logging yet, can this be done via the free version of tunerstudio?, unless its done via other software, i have somthing in my head saying mega log viewer? or something like that? 馃憤
An idea just popped into my head (that doesnt happen often) , i use freezer spray at work a fair bit, next time it happens, ill give the cam sensor a quick spray lol, see what happens, may save me having to do the logging stuff 馃榿
It's done through Tunerstudio. Click on the "Diagnostics & High Speed Loggers" tab. Select "Composite Logger" from the Logger Type. Click Start when the problem appears.
It's done through Tunerstudio. Click on the "Diagnostics & High Speed Loggers" tab. Select "Composite Logger" from the Logger Type. Click Start when the problem appears.
Thank you 馃憤馃憤馃憤

(reading other posts, id say your bang on, my symptoms match others im now reading馃憤馃憤)
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It's done through Tunerstudio. Click on the "Diagnostics & High Speed Loggers" tab. Select "Composite Logger" from the Logger Type. Click Start when the problem appears.
Well at last, now its warm outside, captured it happening. Not sure if the engine is supposed to be running or not when capturing it, but it wasnt, as the car died quickly in traffic and i had to push the car onto the kerb. When trying to start, the fuel relay was not clicking at all, just dead as the car was too hot for the clicking to happen it seems. But the best i could do is below.. Anyone able to understand what im looking at?

Thanks 馃憤馃憤

Computer Personal computer Font Computer keyboard Output device

Computer Laptop Personal computer Computer keyboard Peripheral

Product Font Display device Personal computer Technology

Computer Personal computer Computer keyboard Netbook Peripheral

Computer Font Personal computer Tree Display device



After recording the above (sorry about the damn orientation), i noticed the hidden numbers in the left columb, not sure if thay are whats needed to be seen to diagnose which sensor it is? If so, typically i didnt notice at the time, but some are showing on the first picture above if that helps?
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The cam sensor is dead.
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The cam sensor is dead.
Thank you 馃槺馃憤馃憤馃憤馃憤
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