Fuel Pump Relay noise

[GremlinMKIII]

car specs

1987 Supra 7M-GE

bought the car a while back with 350k km on it (body has a bit of rust, but all in all not so bad) it had a blown up engine the guy had already swapped out for an imported engine with 64k km on it but he never got it running.

the guy didn't connect everything back up properly when he had done the swap himself so myself, my brother and my dad did a rebuild of the new engine and put it back in and hooked it back up (to our knowledge, it's hooked up just fine) but the engine will not start!

first we determined the engine wasn't getting gas, so we took the gas tank out and discovered the fuel pump was in pretty crappy condition, so we replaced that right away and now the engine is indeed getting fuel, but again won't start.

since the day I got it though, it has had a problem with the fuel pump relay making a buzzing noise as soon as you plug in the battery terminals - entire car gets power, everything inside works, but engine won't start (tries to, but just keeps turning with no actual start)

I have scoured the internet for a couple months now trying to figure out a solution to this (haven't been in a big rush due to having my license taken away for medical reasons, but I just got my license back yesterday!! I need my car to start now!) Haven't had any luck finding a solution to this problem - lots of other people having the same problem, but nobody posting a solution.

does ANYONE know what could be goin on???

thanks.

(yes long post, I know..)

[GremlinMKIII]

summary of my last post with just the problem:


7mge
car getting gas but won't start
gets power inside
engine tries to start but doesn't
fuel pump relay makes buzzing noise when you plug the battery in.

[supradaddy0803]

What I would say to look at is the relay becuase unless you push the little screw in on top of your fuel pressure regulator and it hisses a little then there is no pressure there and it will not start. Check the realy per the TSRM mine says with the big lump up on the pin side on the right is one and then 2 on the left. Then at the bottom 3 on the right and 4 on the left. In the plastic cover thingy on the bottom there is a big lump in one side and the other is smaller dont have pick kinda hard to show but I hope you get it. There should be continuity between pins 1 and 3 and none between 2 and 4 if these dont check out then the TSRM calls the relay bad. Also if you apply voltage between 1 and 3 there should be continuity between 2 and 4. Another way to check to see what it is is to short terminals Fp and +B on the check connector and see if you feel pressure on the fuel line. Check out that stuff and let me know what you find and I will look a little further into it to help you out.

[GremlinMKIII]

forgot to mention that I have a total of 3 fuel pump relays and each of them do it. The original owner had replaced it once, and I did when I first noticed the sound.

also, we did check the continuity and it is just fine.
fuel pressure is okay, it's getting to the fuel rail just fine.

[supradaddy0803]

Ok well that narrows it down a bit ohm out your airflow meter plug when you are looking at it there needs to be continuity between the first 2. After that check your ignition timing and spark plugs. if they are wet then they are not firing. Prolly just timing or a ground off somewhere its them little things that kill you.

[GremlinMKIII]

while the sparkplugs may explain it not starting, I still need to figure out the noise from the fuel pump relay :|

I'll have to check the wiring out extensively to check for a grounding issue.

[supramacist]

What's up Gremlin???

Glad to see you found someone who could help you.

[GremlinMKIII]

I've disconnected the AFM as per suggestion of a guy on another supra forum to check to see if the relay is still buzzing which it is.

I have come across some other developments in my troubles with the engine though...

turns out the alarm that was in the car is still in it and it may have a disabler as well - could be the reason for the car not starting? but when I jump Fp and +B in the diagnostic box, while shutting up the fuel pump relay, it causes something in the interior to beep for a few seconds, it stops, then pop! - the doors unlock.. (manual locks, power locks added via the alarm installation)

also, when not jumping Fp / +B and I apply the power - not only does the fuel pump relay buzz, it activates the Main fuse in the fuse box up front.

so, is it possible for a mucked up alarm to draw unnecessary power which activates the Main fuse, which in turn is mucking with the fuel pump relay?

thanks again.

[supradaddy0803]

Sounds liek a alram issue then but usually they have a starter cut off and they just wont turn over but from all the stuff you describing it sounds like that alarm is crapped out. I would find the alarm control box and diconnect it and then try to start it. They usually put them under the dash so that would be the first place to check.

[GremlinMKIII]

ya, my plan is to get into the dash next weekend to try and disconnect that alarm - unfortunately I can only really get to work on my car fri-sun with my schedule.