View Full Version : Fuel/electrical making bad fuel perssure

07-31-2006, 09:57 PM
im 18 and dont know very much about the car i need some help with fuel pressure. my car has all the basic up grades done to it cat back exhaust atr ram air cold air kit plenium plate upgraded intercooler neck ported turbo elbow adjustable fuel pressure regulator upgraded in tank fuel pump adjustable wasegate... my car is an 87 grand national it seems to have a fuel pressure problem. i have it set real high to cut down on the knock before it was low and knocked badly. i turned it up and it really helped according to my gague i have i set at 45psi vaccum on at idle that seems really high compared to other people but i was wondering ware it should be. haveing it this high it made forlower knock it also seems to drop randomly when my turn signal is on and does not like to go up on acceleration making the car lay down and not get any power any ideas on wat is causing my weird fuel pressure problem/electrical problem

07-31-2006, 10:11 PM
Do you have a 'hot wire' setup back to the pump from the back of the alternator? The fuel pump wiring in these cars is very weak. Several vendors offer these: Caspers, Racetronix, etc.

Is your gauge electric?

Does fuel pressure rise with boost?

07-31-2006, 10:50 PM
no i do know that the voltage can be weak back there but another thing i noticed when the fuel pressure starts to go down is the fule pump makes a wining noise like its in over drive and its brand new... but it only happens sometimes and not allt the time its bad...do you think a hot wire kit will solve this problem...the fuel pressure sometimes rises with the boost but only happens sometimes the worst i saw it was the fuel psi when down to 20..it is also a mechanical gauge

08-01-2006, 02:27 AM
Fuel pressure must go up when the boost goes up.

Every TR needs a 'hot wire' kit.

Base pressure should be checked with the hose off at idle for a reference. Do not drive the car this way.

08-01-2006, 09:23 AM
Sounds like possibly the regulator may be bad as well ...

08-01-2006, 10:13 PM
should i replace the regulator and get a hot wire kit or try one first...im also trying to get it ready for next week im going to the track:)

08-02-2006, 05:56 AM
Hot wire kits are a must for these cars. Replacing the regulator is a judgement call. If you have a good regulator (i.e. Accufab) it can be torn down and rebuilt pretty easily. Regulators are ~$100, so its a pricey decision.

08-02-2006, 09:45 PM
thanks i had money to get a regulator so i will find out this weekend if i can really blow those ricer crap boxes away