hesitant power delivery

hi i hope someone can help. i've had the car plugged up and they say its a possible weak signal from imobiliser to fuel pump. the garage gave me a bypass plug but i've looked for the spider imobiliser behind the heater controls and theres nothing there. i've cleaned the sediment catch, replaced the fuel filter and cleaned and wd40'd the injector pump connector jack. i've also checked for 12volts to the fuel stop valve throughout the rev range and checked for leaking intercooler pipes. my car drives fine with usual power half of the time but then decides to go but short of power and anything over 2000ish rev, the revs go up and down eratically and the handbrake light and engine check light also comes on intermittently but not together. is there any way the engine speed sensor or any other sensor could cause this but the diagnosic not pick it up or am i looking at a nackered injector pump or barking up the wrong tree. the car is a 1996 tdies auto, many thanks

if anyone could suggest something i'd really apreciate it. i dont understand why it pulls up to about 50mph without a problem but then hesitates like its short of fuel even on low revs, how does a garage test for a faulty injector pump as they are very very expensive. my guess would be a speed sensor of some kind but the diagnostic says a problem between immobiliser and pump. also why does my handbrake light come on when its acting up. Is the immobiliser built into the ecu as theres no spider behind the dash, thanks

Could be an earth fault.

It's been known for the handbrake to act as the earth causing all sorts of strange electrical problems. I'd check al the earth straps, especially the battery to body but also the engine to body, and the handbrake cable. It's also likely that if it's been doing it a while that the cable gets hot, check for burn marks near to chafing marks etc!!

Could the power problem just be the lift pump on its way out and the electrical problems be unconnected?

i've now sorted the handbrake light which turned out to be a sensitive brake fluid sensor, as for power problem i've narrowed it down to the ecu or the injector pump, my questions are should the injector pump make a loudish buzzing noise which can be heard with the bonnet closed 5 feet from car and should it continue forever till the car is started or just a while, secondly, with mine being an electronic pump can a relpacement be fitted and just work or will it need electrically pairing the the car and imobiliser. answers to these would be most apreciated, thanks for your help. ps my stop solinoid only has 1 wire not 3 that i can see.

benj said:

i've now sorted the handbrake light which turned out to be a sensitive brake fluid sensor, as for power problem i've narrowed it down to the ecu or the injector pump, my questions are should the injector pump make a loudish buzzing noise which can be heard with the bonnet closed 5 feet from car and should it continue forever till the car is started or just a while, secondly, with mine being an electronic pump can a relpacement be fitted and just work or will it need electrically pairing the the car and imobiliser. answers to these would be most apreciated, thanks for your help. ps my stop solinoid only has 1 wire not 3 that i can see.

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can anyone answer these questions? thanks

Apparently the buzzing is normal and is more of a concern if you cant hear it. At least this is what i've gathered from reading other posts.

My non ecu 300tdi only has one wire for the stop solonoid. The whole casing of the IP is grounded so it only needs the single live feed for the solonoid coil.

A buzzing solenoid in my book is a failing solenoid-inside the solenoid you have an electromagnet to pull the plunger up(open valve),against a spring-which closes the valve on power off.When the solenoid is buzzing the two are fighting one another and the plunger is bouncing up and down,opening and closing the fuel flow-I could see this giving issues at large throttle openings-I would change the solenoid if possible.Just my two penneth.