Starts like champ and dies, Can hear fuel pump relay clicking wildly earlier.
08-30-11, 01:24 AM
#1
Starts like champ and dies, Can hear fuel pump relay clicking wildly earlier.
Okay so yesterday while driving I suddenly heard my fuel pump relay click and then a few secounds later my engine died out and I was stranded for a bit.
A few mins later I tried cranking it and it starts up just as strong as always and keeps running.
While I drive a bit more I notice the fuel pump relay going crazy and clicking on and off many times.
And I can tell because my volt meter jumps up every time it clicks off and a few secs later as my fuel pressure dies away the engine dropps dead.
Just like the way it does when I use the fuel cut off switch i installed and hear the relay click off.
At first I thought it was my AFM cuz I know when those go out the fuel pump gets turned off and will only start up but will not keep running.
I went to pick and pull and found another AFM bolted that on No luck.
So now I am wondering what could be the cause of this?
I know for a fact that my fuel pump is good because I put in a Brand new walbro.
The switch for the fuel cut off is good and I even replaced it just to be sure.
The AFM Im still not sure if the one I pulled is working but I will try tomorrow hopefully with one from a working FC.
looking for a wiring diagram of the fuel system so that I can diagnos it myself but with no car to get to the library.
Im kind of stuck at home. Any thoughts on what could be wrong?
P.S. the starting Is still very strong and starts up like a champ. but then when it switches from the starting circuit to the running circuit it dies out.
A few mins later I tried cranking it and it starts up just as strong as always and keeps running.
While I drive a bit more I notice the fuel pump relay going crazy and clicking on and off many times.
And I can tell because my volt meter jumps up every time it clicks off and a few secs later as my fuel pressure dies away the engine dropps dead.
Just like the way it does when I use the fuel cut off switch i installed and hear the relay click off.
At first I thought it was my AFM cuz I know when those go out the fuel pump gets turned off and will only start up but will not keep running.
I went to pick and pull and found another AFM bolted that on No luck.
So now I am wondering what could be the cause of this?
I know for a fact that my fuel pump is good because I put in a Brand new walbro.
The switch for the fuel cut off is good and I even replaced it just to be sure.
The AFM Im still not sure if the one I pulled is working but I will try tomorrow hopefully with one from a working FC.
looking for a wiring diagram of the fuel system so that I can diagnos it myself but with no car to get to the library.
Im kind of stuck at home. Any thoughts on what could be wrong?
P.S. the starting Is still very strong and starts up like a champ. but then when it switches from the starting circuit to the running circuit it dies out.
08-30-11, 02:27 PM
#2
You could start off by jumpering the fuel check connector. The problem could be the Circuit Opening relay, which you are calling the fuel pump relay. Or it could be the fuel switch in the AFM or perhaps a faulty connection at the AFM or perhaps a faulty ground.
When the car is started and the engine rpm climbs over 500 rpm the AFM assists in providing the ground signal to the relay to keep the car running. So jumpering the fuel check connector ought to tell you something. Jumpering the connector bypasses the AFM. If this jumpering doesn't change things for the better than you could use the solid Black wire in the Circuit Opening relay as your ground source for the relay as it is a constant ground while the ground coming from the AFM is not constant but becomes a temporary ground once the rpm climbs above 500 and stays there (ie. a running car).
The solid Black wire in the relay would be jumpered to the Brown wire in the same relay. Don't confuse the solid Black wire w/the Black/White wire carrying voltage w/key to on that is nestled right next to the solid Black wire.
When the car is started and the engine rpm climbs over 500 rpm the AFM assists in providing the ground signal to the relay to keep the car running. So jumpering the fuel check connector ought to tell you something. Jumpering the connector bypasses the AFM. If this jumpering doesn't change things for the better than you could use the solid Black wire in the Circuit Opening relay as your ground source for the relay as it is a constant ground while the ground coming from the AFM is not constant but becomes a temporary ground once the rpm climbs above 500 and stays there (ie. a running car).
The solid Black wire in the relay would be jumpered to the Brown wire in the same relay. Don't confuse the solid Black wire w/the Black/White wire carrying voltage w/key to on that is nestled right next to the solid Black wire.
09-01-11, 12:54 AM
#3
Fixed~
Okay so I jumpered the fuel check plug (cant believe i forgot about that thing, used it when i was diagnosing a bad fuel pump) and it stayed alive so its just a bad AFM. I replaced the AFM with one I found off an 87. Its good now but Im wondering how often these fail because Ive read about this issue on the forums before and it seems like a sort of common problem. Well Im just glad that in the case it fails again I can grab my 10Gauge jumper wire and at least get myself back home safely. So now my hunt for a spare AFM begins. Hmm I also wonder if there is a way to use a S5 MAF, I know the signal is different and uses only 5 pins? in the connecter VS 7 in the AFM, but I also read on a thread that a simple translator could be made with 10 bucks. So im thinking if only this could be done, then the failing S4 AFM could be replaced with reliable S5 MAFs.
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