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Electrical guru wanted

Posted: Sun Feb 17, 2013 9:48 am
by OLD FART
Have just refitted my cleaned fuel tank along with a 944 pump with a new pre pump and pre fuel rail filters . All hoses and wires in right places and tried to start motor and it ran for a few seconds and stopped. There is app half full pre tank filter ( would have thought that it should have filled right up if pump was working) so the pump must have worked but car won't start :x
Have checked dash fuse box and all ok so is there another fuse/relay that looks after the pump and if so where is it ??
Any helpful suggestions appreciated :)
Can I check to see if there is power at the pump with a test light by clipping onto the "+" terminal and connecting to the other to earth on the car or to the earth terminal on the pump ??
Is the anti backflow valve really needed on the outlet end of the pump ??

PS electrics are black magic to me :oops: LOL

Posted: Sun Feb 17, 2013 11:13 am
by iXNAY
so your not getting fuel pressure to the injector rail?

im not sure if a test light will work but you can go get a cheap multimeter that will work and see if there is juice going to the pump

but just as easy would be pull the line off the fuel rail and see if it pisses out when you turn the ignition on

Posted: Sun Feb 17, 2013 11:43 am
by OLD FART
iXNAY wrote:so your not getting fuel pressure to the injector rail?

im not sure if a test light will work but you can go get a cheap multimeter that will work and see if there is juice going to the pump

but just as easy would be pull the line off the fuel rail and see if it pisses out when you turn the ignition on
When ign is on can't hear/feel anything from the pump. Have heard that they are quite noisy.
When I originally had the stock pump replaced many years ago the new one had to be replaced as it was faulty. Lightning doesn't strike the same place twice so I have been told :wtf:

Posted: Sun Feb 17, 2013 1:51 pm
by OLD FART
Phoned Dave (Redzone) who told me the pump relay is in passengers footwell near the computer so took cover off and found a loose 3pin connector have sent pic of it to Lee and waiting to hear from him before I put it together as don't want to make matters worse by putting it together if it shouldn't be so fingers xxxx that this is the end of my problems :?

Re: Electrical guru wanted

Posted: Sun Feb 17, 2013 8:22 pm
by 1320ft
OLD FART wrote: Is the anti backflow valve really needed on the outlet end of the pump ??
yes

Posted: Mon Feb 18, 2013 9:52 am
by dirtygalant
what ECU are you running? the factory ECU wont fun the pump until it knows the engine is cranking - so when you turn the ignition on and the engine not yet running the pump will not be running (it may run for a second or two initially to prime). Once the ECU knows the starter is being triggered and that the engine is running (crank signal) only then it will send power to trigger the fuel pump relay.

Posted: Mon Feb 18, 2013 10:32 am
by OLD FART
dirtygalant wrote:what ECU are you running? the factory ECU wont fun the pump until it knows the engine is cranking - so when you turn the ignition on and the engine not yet running the pump will not be running (it may run for a second or two initially to prime). Once the ECU knows the starter is being triggered and that the engine is running (crank signal) only then it will send power to trigger the fuel pump relay.
Haltec E6X
Will run a test wire from battery + to pump + to rule out faulty pump.

Posted: Mon Feb 18, 2013 10:11 pm
by panda
I'm using a Haltech E6 in my MPI set up & when the ignition is first turned on, the ECU operates the fuel pump relay for about 5 seconds, after which the pump will stop unless the ECU is receives ignition trigger pulses which then keeps the fuel pump relay operated.
Several checks can be done, firstly connect 12 volts direct to the pump & check that its actually pumps fuel at the required rate & pressure.
Secondly, check that the fuel pump relay thats driven from the Haltech ECU is actually operating when it should. Usually you can hear it click when switching on or off.
Also Haltech usually have a dedicated fuel pump fuse in the small fuse strip that has the 3 little fuses in it. Check that the fuse isn't blown, damaged or not seating correctly.

Posted: Mon Feb 18, 2013 11:04 pm
by niss720
Could be the pump its self, I fitted a Bosch pump in my JB, ran new wires and a relay triggered by the stinger ecu, when turning on the ignition I could hear an Initial clunk from the fuel pump but no continual buzz. :x Only after an attempt to start it did I realise the pump didnt work so had to drop the tank again and connected it to 12v and fuel only trickled out of it :roll: , another couple hundred for a new Bosch 044 and problem solvered :twisted:

Posted: Tue Feb 19, 2013 7:13 am
by 1320ft
You have to be careful & remember that Bosch pumps are not designed to suck & push at the same time. They are designed to be fed, thats why the VLT uses a small lift pump etc.

Posted: Tue Feb 19, 2013 6:57 pm
by thrash
also, I may be remembering this wrong, but those pumps require a larger amount of current going through the wires - if your wires are undersized for the pump's demands, they will start to get extremely hot, and burn through the insulation and possibly short out

perhaps as a safety either replace the wires completely, oe have them checked + run an extra set to double up?

Posted: Tue Feb 19, 2013 9:58 pm
by RiceThief
thrash wrote:also, I may be remembering this wrong, but those pumps require a larger amount of current going through the wires - if your wires are undersized for the pump's demands, they will start to get extremely hot, and burn through the insulation and possibly short out

perhaps as a safety either replace the wires completely, oe have them checked + run an extra set to double up?
Im pretty sure if you don't get enough current through a pump like a 044, it just won't flow to its full potential. Thats why its recommended to run it directly from the battery with a relay.

Posted: Wed Feb 20, 2013 8:18 am
by OLD FART
Its alive :D took all the 4 fuses in the Haltec fuse block and there seemed to be a bit of white on the blades so sprayed fuses & block with contact cleaner and blew block out with compressed and put it all back together and hey presto fired up 1st crank so now no more of this :( and now I look more like this :D again.

Posted: Wed Feb 20, 2013 8:40 am
by redzone
90% of electrical problems are caused by bad/frosty connections :)