Need help, or I'm gonna get canned!!!

[DangerangerHD]

Ok, guy at the parts store is trying to convince me that the relay kicks over to a seperate power source after the truck is started (does connection 87a controll this?). and this could be the problem, he wants me to hot wire the relay connections, can someone tell me wtf he's talking about and how to do it?. Something about a oil pressure switch(?) or my ecu. Wow my heads spinning from too much info, time to fry a bowl and let it sink in. Next car I buy will have a carburator and be from the 60's.

 

[Earl43P]

I dont think its the relay I switched it out with my eec and truck still dies after a few seconds. I turned on the ignition to run and start and pumps whining fine. Attached meter to leads that attach to the pump and got 11V at prime, 6.6V after Prime, and 10.3V while turning motor. Sound right or too low?

Those voltages sound right, except for the 6.6v after prime, very puzzling, I'd expect 0v.


How sloppy is your ignition? There is linkage from the key to the switch itself. That area could be your problem. As bad as it sounds (I mean this as a one-time test) will it continue to run if you keep cranking the starter?

Yeah, I'm saying don't release the key, let that starter continue even after the engine is running. If it runs and doesn't die, I suspect ignition switch.

It won't KILL the starter to test it like that one time. You may already know that answer from all your start attempts.

 

[Earl43P]

I can send you schematics, but I need your e-mail address.

Ready to send.

 

[slimchriz]

Ok, guy at the parts store is trying to convince me that the relay kicks over to a seperate power source after the truck is started (does connection 87a controll this?). and this could be the problem, he wants me to hot wire the relay connections, can someone tell me wtf he's talking about and how to do it?. Something about a oil pressure switch(?) or my ecu. Wow my heads spinning from too much info, time to fry a bowl and let it sink in. Next car I buy will have a carburator and be from the 60's.

Err separate power source? no basically a relay is a switch that is activated my an electromagnet the ignition switch activates this electromagnet ok... so what this magnet does is when its turn on it pulls a lead/wire (usually one with power) to a contact that goes out to the FP (or whatever its hooked up to switch on) now what this guys is saying is its switches to another power source is not possible.....Because the only other point to have power in that relay is another lead that is contacting the output(FP) when the magnet is NOT activated.....so basically when car is off this is the one contacting the FP and since you dont need power to FP when car is off it makes no sense .

The thing to do is check power at FP or like someone said test it in bucket...

Dont know if its been suggested or asked but do you have a new Fuel filter?

 

[DangerangerHD]

Those voltages sound right, except for the 6.6v after prime, very puzzling, I'd expect 0v.


How sloppy is your ignition? There is linkage from the key to the switch itself. That area could be your problem. As bad as it sounds (I mean this as a one-time test) will it continue to run if you keep cranking the starter?

Yeah, I'm saying don't release the key, let that starter continue even after the engine is running. If it runs and doesn't die, I suspect ignition switch.

It won't KILL the starter to test it like that one time. You may already know that answer from all your start attempts.

The ignition feels tight when I turn it, If I keep the starter going the engine tries to die, then goes to all starter, the fires again and sputers/runs rough, so on and so forth. Good for as long as I have the starter going. Also Ive been able at times to feather the throttle just right (lots of feathering) and it runs, but rough. Too much throttle and it stalls, to little it dies, too long at steady rpm starts to choke. Its the most sparatic fuel flow ever. If i disconect fuel line before the filter sometimes it spits on prime, sometimes not. Sometimes it doesent prime but spits on crank, sometimes doesnt do anything, other times it starts slow (couple turns) then dies. Real Wierd.

I will be testing the pump on a bucket shortly, can I use a battery charger (slow trickle type) to bech test it or should i just hook it to a battery?

 

[Earl43P]

Ok, guy at the parts store is trying to convince me that the relay kicks over to a seperate power source after the truck is started (does connection 87a controll this?). and this could be the problem, he wants me to hot wire the relay connections, can someone tell me wtf he's talking about and how to do it?. Something about a oil pressure switch(?) or my ecu. Wow my heads spinning from too much info, time to fry a bowl and let it sink in. Next car I buy will have a carburator and be from the 60's.

The switching function he is talking about is true.

But yours is done by the ignition switch applying power to the PCM relay in Start, then Run. That's all the switching. Remember, the PCM relay CONTROLS power to activate the FP relay, so if the PCM relay fails (from a bad ignition switch) the FP can't run either.

There is no oil pressure interlock though.

 

[Earl43P]

The ignition feels tight when I turn it, If I keep the starter going the engine tries to die, then goes to all starter, the fires again and sputers/runs rough, so on and so forth. Good for as long as I have the starter going. Also Ive been able at times to feather the throttle just right (lots of feathering) and it runs, but rough. Too much throttle and it stalls, to little it dies, too long at steady rpm starts to choke. Its the most sparatic fuel flow ever. If i disconect fuel line before the filter sometimes it spits on prime, sometimes not. Sometimes it doesent prime but spits on crank, sometimes doesnt do anything, other times it starts slow (couple turns) then dies. Real Wierd.

Sounds like a bad pump.

I'd still throw a light on the PK/BK wire at the inertia switch so you KNOW power is getting there. If the light is out, it's NOT the pump.

I bought a fuel pump (only) for one of my 93's. Guy I sold it to later had to replace that pump again, months later. Turns out the piece of tubing they supplied was not fuel compatible, it deteriorated and leaked and the pump quit eventually.

You haven't given me an e-mail address so I can send you this info. Trust me, you want this stuff.

 

[Earl43P]

I will be testing the pump on a bucket shortly, can I use a battery charger (slow trickle type) to bech test it or should i just hook it to a battery?

I'd leave it installed and put 12v to the PK/BK wire at the inertia switch. That way uses all its wiring.

A typical trickle charger will not supply 12v to power a FP, no way, no how. Use the battery.


You haven't given me an e-mail address so I can send you this info. Trust me, you want this stuff.

--------------------------------------------------------------------------------

 

[DangerangerHD]

getting 10.3V behind the inertia switch. Brakelights AOK, and put in a new relay still spastic.

 

[Earl43P]

Inertia switch has 2 wires, do both have 10.3v with inertia switch connected?

I'm assuming you took that voltage readings @ the Fuel Tank connector, with it disconnected (top of the tank)? Try using a different ground or just the plug for the tank?

Lastly, is the battery fully charged?

 

[DangerangerHD]

Inertia switch has 2 wires, do both have 10.3v with inertia switch connected?

I'm assuming you took that voltage readings @ the Fuel Tank connector, with it disconnected (top of the tank)? Try using a different ground or just the plug for the tank?

Lastly, is the battery fully charged?

The readings came from the wires that directly conect to the fuel pump. I unpluged the pump and attached the meter to the femal conectors coming from the backside of the plug. The most recent 10.3V measurement was from the pk/bk wire off the inertia switch. The battery is probably low now from all the cranking but it stills turns quick.

 

[DangerangerHD]

Bench tested ebay pump and it works fine
bench tested oem pump also fine
reinstalled oem pump
put 2.5 gal new gas in.
starts and runs fine.... today
Probably bad gas.
That being said I have a almost new ebay pump Ill sell for 50 bucks lol.

 

[slimchriz]

Wow that would have save an ass load of time if you knew that first eh?

You might have debris in the line going to the filter I would check the tank as well dont know how anything would get in there but obviously something blocks the flow

 

[DangerangerHD]

Wow that would have save an ass load of time if you knew that first eh?

You might have debris in the line going to the filter I would check the tank as well dont know how anything would get in there but obviously something blocks the flow

Yeah, but it has done this before. I am not getting my hopes up just yet.

 

[poof_596]

Well, let's look at what you've done. You suspected the fuel pump, so you put a new one in. You now have the same symptoms. I would stop, for now, with the fuel pump and start looking at things upstream from the fuel pump (wiring, etc.). I know it's easy to blame the fuel pump, because that's something easily fixed/replaced, but if it were me, I would assume that two fuel pumps doing the same thing means that it's not the problem. It's a possibility, but it's a lesser possibility than some other things.</soapbox>

Going by an online repair manual, steps for diagnosing are:

1. Checking voltage at the connector
2. Checking inertia switch for continuity
3. Checking to make sure the connector is not loose or open at the fuel pump
4. Checking the relay by manually energizing it (grounding it)
5. Checking for plugged fuel lines

And if you're really into having fun, you might get a 5 gallon bucket, some hose, and trying to bench test the fuel pump to see if it's really the problem.

I know you said you don't have a multimeter nor how to use one, but if you want to fix problems like this by yourself, you're going to need to get and learn to use one, unfortunately. It's much cheaper than throwing parts at it...

I HAD a 2000 GMC Sonoma, I put three fuel pumps in it in about a month! Talk about wasting my time. It turned out to be the wires going to the fuel pump, but NOT the wires themselves, they were fine. The plug(or socket) end of the wire was bad. Just a thought.