Technical Starting problems

[gabbiano]

Hi all...
I would appreciate if anyone could help me with a small information regarding starting bravo 1,6 16V.
The problem is strange and it is as follows:
When I turn my key into 2nd position (before starter position) I allways keep hearing the hum of the fuel pump from behind. But not all of the time. Sometimes when engine is hot, fuel pump does not work at all, but engine still starts fine. I guess this is because there is no need for fuel pump to work, if the pressure of the fuel in injector is still high. When my engine starts, then it starts in a second, but sometimes it just won't...I keep starting it for minutes until it somehow starts. Then, if I turn off the engine and tra to start again, then There is no problems at all, again it starts in a second.
My question is, does fuel pump allways have to work when I turn the key in 2nd position, or not. What controls the relay of the fuel pump...is it some pressure indicator valve in the injector or anywhere else in the fuel system or what. Could this be the reason of my recent nightmares...
Once again, I'd be happy if anyone could help me with this one, especially if he had some similar problems....

 

[peterdea]

I have had the same problem with my Brava 1.6 which has dragged on for months and in the end resorted to a garage. After trying the several things they concluded it was a weak fuel pump. This has now been replaced (not cheep) and has solved this starting problem. To answer your question re the fuel pressure regulation, this is an integral part of the pump itself.

 

[blackburnsei]

Ooooh interesting, im getting the exact same at the moment. Booked in for garage on tuesday.

Ali

 

[jug]

first start of the day the fuel pump will always need to build up pressure as it will be lost over time, however if you have used the car recently (within a couple of hours) then the pressure is very likely to be at the required level meaning the pump does not need to prime when ignition is switched on.

a pump producing low pressure or a slow pressure build up is often suffering from a blockage in the filter, which is especially likely on the 1.6 as the filter is built into the pump. you could try taking yours off and cleaning it up a bit. try wiring it backwards when removed to reverse flush the filter, use home made fuel lines (hose pipe lengths) in a bucket of petrol. if you reverse the ignition live and earth on the pump it should pump backwards clearing the filter.

if that doesnt fix the problem go to a scrapyard and remove the whole pump assembly from a 1.6 bravo/a. you can access it via the plastic cover under the boot carpet. its a white round plastic cover iirc. should cost £10 for the pump. its an easy job

 

[jug]

by the way gabbiano i've heard the petrol in croatia isnt very good quality, you should use redex or a similar fuel injection system cleaner regularly on your car.

 

[blackburnsei]

When it does start first time the fuel pump can be heard priming, like a click (probably fuel relay) followed by a hum then a clunk (Click-mmmmmmmmmmmm-Clunk) However, when it is playing silly beggers and wont start this cant be heard.

Mechanic suggested it may be an ignition wiring issue. Pump does turn over once engine running. Will consult wiring diagrams later to see what sence i can make of things.

 

[blackburnsei]

Well, ive got to have a new set of coils as the resistance drops heavily when warm and a new fuel pump because its weak.