Jump to content
HybridZ

rough idle except when fuel pump relay removed??


Recommended Posts

I recently got my car started aftering being in several pieces for about 2 years. I was having trouble getting it to start, thought maybe it was flooded,  and disconnected the fuel pump relay and fuel pump contol relay(I think its called) in hopes of getting some fuel out. Well it fired right up after that, idled at aroun 1100 rpm and continued running for some reason until I killed it. Plugged relays in and it starts, but idles at under 500rpm, is shaky, and smokes a lot. rotating the distributor doesn't really fix anything. If i get on the gas, it stalls and wont start again. Disconnect the relays again, It starts. idles smooth, and runs until I give it gas or turn the key. Reconnect relays, back to bad idle, smokey, and stalls as soon as I get on gas. Any input? Advice? Does this sound like something may be wrong with my fuel delivery? Timing? Something electrical? Thanks in advance

Link to comment
Share on other sites

Put a fuel pressure gauge on the feed line.

My bet is you're plugged on the return from sitting, and when you restarted after all that time all the swarf in the lines passed back to the tank and plugged at the return line elbow just inside the tank.

 

A coat hangar, vice grips, and hammer to punch through it will restore it to operation.

 

Don't continue flooding it, you're washing the hell out f your cylinder walls!

Link to comment
Share on other sites

Update: I installed the fuel guage and ran some wire through the tanks return to see if it was clogged. There was something muddy on the wire after running it through a few times, but I did get the wire in to go in pretty far after a while. Guessing it may have been rust, or hopefully one of those stupid mud wasps didn't make their way in. (usually had the lines taped off, but for a couple days it was exposed.) Anyway I went a head and installed a see through fuel filter from the tank to the fuel pump, and a new fuel filter up front. What I am noticing is that after starting the car while cold, the fuel pressure goes to around 30psi and it idles decent for a little while, then shortly after, it starts idling poor again, fuel pressure drops to like 18-20, then it cuts off. After that, it really wont start. I went to look at the fuel filter between the tank and fuel pump and it is pretty empty, not much fuel made its way in, so now I am guessing the fuel pump is dying?

 

skirkland1980: I am using the distributor that came with the car. Guess I should mention the car has the stock l28e and is a 1978 280z. Thanks for response

Link to comment
Share on other sites

Update: Removed the small cone shaped strainer and it appeared clean. Also the hose to the inlet was dry. Pump is getting current when attempting to start, so at this point I am guessing the pump has gone out. Last attempt, I will buy a bit more fuel and see if that makes any difference, probably wont. But if that fails, I am off to the parts store to get another pump unless someone knows something I don't. Will post results later.

Edited by heavyweight280
Link to comment
Share on other sites

Update: Removed the small cone shaped strainer and it appeared clean. Also the hose to the inlet was dry. Pump is getting current when attempting to start, so at this point I am guessing the pump has gone out. Last attempt, I will buy a bit more fuel and see if that makes any difference, probably wont. But if that fails, I am off to the parts store to get another pump unless someone knows something I don't. Will post results later.

Sounds like a good plan .

  • Like 1
Link to comment
Share on other sites

"I will buy a bit more fuel and see if that makes any difference, probably wont."

 

NEVER NEVER NEVER, EVER troubleshoot fuel issues with an almost empty tank.

 

This one sounds like it's gonna have a "Sling Blade Lawnmower Solution" to it: 'tain't gets n'er gas in tchere, uhm hum!

 

You can mail me my biscuits 'n musterd ...

Link to comment
Share on other sites

"I will buy a bit more fuel and see if that makes any difference, probably wont."

 

NEVER NEVER NEVER, EVER troubleshoot fuel issues with an almost empty tank.

 

This one sounds like it's gonna have a "Sling Blade Lawnmower Solution" to it: 'tain't gets n'er gas in tchere, uhm hum!

 

You can mail me my biscuits 'n musterd ...

 

 

I had 4 gallons in there at first, just went to put 2 more, but made no real difference.

New pump is in, finally getting fuel again. Idle still bad. Now the guage reads around 40psi, slow idle, smoke. Turned it off and it wont start up again... Thinking of taking it in to mechanic at this point, no more free time to play with it.

Link to comment
Share on other sites

If you can get it to run again , I would let it run for awhile before you shut it off . You said the car sat for 2 yrs , poss . that you still have bad fuel in it . Might want to put some fuel injector cleaner in the tank . Highly rec Chevron Techron .

Link to comment
Share on other sites

If you can get it to run again , I would let it run for awhile before you shut it off . You said the car sat for 2 yrs , poss . that you still have bad fuel in it . Might want to put some fuel injector cleaner in the tank . Highly rec Chevron Techron .

Well I had removed the tank as well so the old gas was drained.  I did put some injector cleaner and premium from citgo. Anyways, here are a couple vids of what it is like atm. Unfortunately, my free time ended, gonna have to take it to a mechanic. It is probably something really small  and I came a along way from where it was, but yeah... Anyways, will post what was wrong with it when i find out.

http://www.youtube.com/watch?v=Ym8Tn0f9c24

http://www.youtube.com/watch?v=sTt82gddI28

Link to comment
Share on other sites

I

 

The first vdo shows low fuel press. and which side of the pump is the clear plastic fuel filter mounted ?

I actually noticed that on the youtube vid. It started around 40psi, and gradually made its way down to around 20. I let it run for like 10ish-15ish minutes and it died about 3-4 mins after I stopped filming. And the clear filter is between the tank and the fuel pump inlet.

Link to comment
Share on other sites

Either you have restriction , bad pump , voltage problem to pump , bad fuel press regulator .

 

Pinch the fuel return line to see if press goes up . If yes , poss bad regulator ( further diag  required )

By-pass fuel pump control circuit with separate power and ground wires to pump ( good size wire ) to test voltage drop problem . If press. is ok , then you might have voltage drop problem .

Link to comment
Share on other sites

  • 4 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...