budget builder

iTrader: (3)

new pump, strainer and and filter in former v6 car converted to 600 holley using a tbi fuel pump currently. and a Mallory reg. of course gauge and small metal filter right befor carb. the car can be running and all of a sudden the pressure drops off to 0. then all of a sudden back up to 6.5.


sometimes it will do this a couple times and then the engine die. I checked the fuel filter at carb (don't kno y I just thought about checking the one at frame rail at tank) #duh. pump could be having a hard time if its clogged. the one at carb is not its fine.


maybe its b/c the oem engine is out but the oil pressure sensor doesn't seem to kick the pump "on" when the engine is turning over either. switch on it will prime and shut off then while cranking and oil press comes up, no fuel. if I tap the regulator or it fires up then it will run fine until the pressure decides to drop off


########PLEASE TELL ME I DONT HAVE TO DROP TANK AGAIN###


If I do this time I get a WALBRO. as I said I will jack it up and check the frame rail filter when I get home. if clogged I will replace. I just had to replace ground cable from battery to block.

Ozz1967

iTrader: (4)

the oil pressure sensor shouldn't care what engine is in the car since it only cares about having oil pressure or not.

It's possible the pump is bad or the relay is faulty causing intermittent voltage to the pump.

Where are you taking the fuel pressure reading? Off the port from the regulator or somewhere else?

budget builder

iTrader: (3)

hadn't thought about relay. im just looking at the inline fuel pressure gauge after the reg. before the carb. I have a stand alone pressure tester and will try putting that on it tday.

budget builder

iTrader: (3)

did get around to taking the big fuel filter off it was partially restricted. takes some effort to blow thru. I think the fuel pump I used was an ( AIRTEX E3902) IF and I do mean IF I have to drop the tank again what do you all recommend?

budget builder

iTrader: (3)

New filter and relay doing same thing. Im wondering if the oil pressure switch is showing pressuer on the gauge on instrument cluster but not at actual computer.

Did I mess up putting the low pressure fuel pump from a tbi system instead of the oem for 3.1L? I thought as long as it was for a carb conversion and all I needed was 6-7psi it would be ok.

budget builder

iTrader: (3)

Theory: get under car let wife try to keep it running use dvom to see if ever lose voltage if yes=electric problem. If no=fuel pump. And this time a quality one or oem. Right or wrong?

budget builder

iTrader: (3)

got it,


I supplied batt volt directly to pump and it worked so I reconnected the pump to backseat connector and went to the relay connector and jumped a to e b/c the pump working doesn't mean its pushing proper pressure. so I made it so the pump would run all the time thru the Mallory reg. and the gauge started reading 15psi and then I adjusted down to 6.5psi. fired it up let it run and so far so good. looks like it was 2 bad relays one old and one new. thx fellas.

budget builder

iTrader: (3)

H E L P!!!!!!!

Ok 3relays and still got something wierd happening. As long as I bypass the relay connector I have 6.5 when I connect relay pressure falls off to 5.5 and sometimes no pressure, sometimes take a long time to build pressure from 0,

Reconnect jumper back to 6.5. Please help. Apparently the power has no problem from relay connector to fuel pump so the problem has to be forcing and keeping voltage in the relay in the on position

budget builder

iTrader: (3)

ok, heres what I did. I connect orange to grey the fuel pump runs I get good pressure if I disconnect jumper and put in relay the pressure drops slightly, sometimes completely, if I shut the car off and restart some times the inline fuel gauge reads zero and after a few seconds slowly builds to 6.5psi.


I didn't have diagram last night but when I get home today im checking for 12v on red prime, org, and dk grn and wht. then checking for continuity on blk/wt b4 I try to start. with and w/o the key in start/run. I will report findings. then I will (dangerous) check for full 12v at rear **behind the backseat connector** while car is running and not running when it is supposed to be priming.


somewhere for some reason it is dropping voltage and only seems to be doing it while the relay is in. b/c while jumping to g port or from a to e on relay connector it seems to be running fine. If im missing something feel free to let me know..


edit: Mallory 4309, sum-g1710, sum-800115, Delphi fe0115 all from summit, no leaks. I would say maybe the reg needs rebuilding but all of this is about one year old.

budget builder

iTrader: (3)

1. running: I have 14v on orange, 12.5v on grey, .52v on dk grn/wht, 0v on red. 6.5psi on gauge.


2. cturned car off and then pat gas once turn key and: 0psi while running, 14.5v orange, 0.5v grey, .52 dkgrn/wht, 0v red, and yes fuel pump actually came on and primed (relay was connected and then when 0psi was observed then was relay disconnected and readings took) which tells me that sometimes the OPSU is not sending voltage even when the car is indeed running.


****oh im running a 600cfm carb**** so the car can run a little while the FP is not running.


after test #2 I plugged the relay back in and slowly the gauge psi came back to 6.5x but isn't the OPSU supposed to supply voltage after the car is running in case the relay drops voltage? and what is stopping the relay (3 of them) not to connect to run even when the orange is holding constant to 12-14.5v? the grn/wht connect to a11 on the ecm what does that wire do? is this y the relay is not switching over to run sometimes or causing the relay to switch back over to off ##AKA: the grey wire lose voltage?
what does the FP prime connector (red) go? and is that all it does?


im not hard to get along with if im doing something wrong please tell me ive made several posts and no response. I just need to kno am I missing something or doing something completely bass ackwards. HELP
but I don't think the FP is the problem. ground maybe?

budget builder

iTrader: (3)

Got it thx to "electronics" board it was a fried OPSU. Put in a new one and now the relay clicks twice and car fires right up.