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Author Topic: Fuel pump  (Read 3592 times)
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« on: 28 June, 2008, 02:34:49 PM »

Advice please. My 16v was slow to start this morning and after taking it for a run I left it for a half hour tried it again and it was worse.
Checked the fuel pump which was ok and also the fuel pump relays which are ok. One thing I found out was the pump wasnt priming. Normally when you switch on the ignition you can hear the pump run for a second or two and it then stops until the engine is turned over. When you switch the ignition on the relays are clicking for a fraction of a second only.Once the engine fires the pump is fine. There must be a ecu sensor linked into the fuel pump,anyone know which one it may be, or any other ideas to check?
Neil Lewis
« Reply #1 on: 29 June, 2008, 10:13:10 AM »

The pumps relays are controlled by a circuit in the ECU.  The ECU makes the fuel pump run for a few seconds at ignition on then keeps the pump going so long as there are engine revs.  It's unlikely that the RPM signal is not getting through so the pump not running could be due to a few of things:

1) The contacts on the relays are poor.  Both relays in the scuttle area control the fuel pump.  One controls the main power and the other switches the pump on and off.  Because those relays are open to teh elements their contacts can get mightily corroded.  Even if the relays click, they may not be providing enough power to run the fuel pump.  So give the relay sockets and pins a good clean and coat them with a "very" light smear of copper grease.  Replacing the relays is easy; they're about a fiver each!

2) More of a problem is the transistor inside the ECU.  I had this with the circuit which drives the injectors; one of the injectors would work sometime and not at others.  It turned out to be a simple dry joint on the printed circuit board which I remade by touching a soldering iron to all the joints to reflow the solder around the component pins.  The ECU is found underneath the radio and comes out and can be dismantled fairly easily.

3) While I was about 2) above, I dicovered that the wiring harness leading to the ECU was full of water.  I was worried that this might cause electricity to "leak" out of the wires.  I stripped back all the black tape, left it to dry for a while and retaped it.  I never did find where the water was coming from.

Probably not a fix for your problem but some things which have happend to me and should be looked at by everyone with an Integrale (and other similarly equipped Lancias/Fiats/Alfas).

1) The two short lengths cotton covered rubber hose which connect the fuel pump to the pipes which lead to the engine can perish and split.  These are located inside the fuel tank and link the fuel pump to a copper fuel cooling coil and from there to the tank outlet.  Once the fuel pump is removed from the tank (relatively) easy, these two pipes can be replaced with modern fuel injection hose.  Both lengths are about 2 inches long and attached by jubilee clips.  Barry Waterhouse used to supply these ready cut but it's no problem to make your own using hose from the local parts shop.

2) I actually had the outlet nozzle on my fuel pump snap off.  There are two types of pump, one has a metal outlet (so no problems there) and the other has a plastic one (which was mine).  This stopped me dead at the side of the road; I could hear the pump running but no fuel was getting to the engine.  I'm a resorseful chap so I whittled what remained of the nozzle with my swiss army knife and forced the aforementioned hose back on.  The only real solution is to replace the whole pump at a cost of 80-100.

3) The cotton covered hose in the engine bay which connects to the fuel filter can perish and split.  I had this happen on both my integrales and it caused a lot of petrol to spray out over the exhaust downpipe.  The smell was overpowering but it could have resulted in a fire Shocked.  Like the tank hoses this can be replaced with a length of modern fuel injection hose and jubilee clip; about 2 feet if I recall correctly.  Getting the old hose off the joint at the engine fire wall is a real pig  Sad

4) The short length of narrow bore rubber hose which links the fuel pressure regulator regulator to the inlet manifold can crack.  This prevents the fuel regulator from adjusting itself to the manifold pressure causing a weak mixture on acceleration which isn't good for engine life.  The hose is very easy to replace and should be checked at yearly intervals.

I remember hearing tales of the Rover 2.7 V6 engine having all sorts of running problems and it was traced back to this small piece of hose.  It took the Honad technicians weeks to find Cheesy

5) The fuel pressure regulator on the end of the fuel injection rail can wear causing the fuel pressure to the injectors to drop.  This causes the engine to run roughly on acceleration.  A new regulator is quite expensive but, since it's the same one which fits Escort Cosworths, they come up regularly on Ebay at about 40.  Don't fit a FSE power boost valve.  They seem liek a good idea but, even when adjusted correctly, you'll just end up using lots more fuel and washing the oil off the cylinder walls because of that excess.  Not good for cylinder life.

So, as usual I've gone on a bit.  But these are all real problems which have affected me over 12 years and 140,000 miles of Integrale ownership.

« Reply #2 on: 29 June, 2008, 11:38:46 AM »

Many thanks Neil, lots of food for thought and a comprehensive answer. Smiley I took the relays out checked them as best as I could ,all seemed ok. But for the sake of a few quid I will replace them anyway next week.I connected a temporary test wire to the relay output to the pump with a bulb so I can see exactly whats happening. The pump is running fine when the engine is running ,but  in pre ignition stage ,both with a hot and cold engine the power to the pump is on for a split fraction of a second. The fuel lines have been replaced from the tank forward. I'm inclined to think your idea of a transistor or dry circuit in the ecu may be the culprit
Anyway the car is running and as I am coming over the the AGM next week all the way from the west of Ireland , so hopefully I wont arrive on the back of an AA truck Sad Shocked.
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