Pennock's Fiero Forum
  Technical Discussion & Questions
  Fuel pump problem

Post New Topic  Post A Reply
Email This Page to Someone! | Printable Version


next newest topic | next oldest topic
Fuel pump problem by vladfiero
Started on: 08-03-2013 12:51 PM
Replies: 11 (2341 views)
Last post by: vladfiero on 10-23-2013 09:01 PM
vladfiero
Member
Posts: 45
From: La Prarie, Quebec, Canada
Registered: Feb 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-03-2013 12:51 PM Click Here to See the Profile for vladfieroClick Here to Email vladfieroSend a Private Message to vladfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a problem with my fuel system, in my 1984 fiero with the 2.5l , the pump doesn't prime when I turn on the key. I bypassed the relay to see if the pump was the problem but when I do I hear the pump running but even then there seems to be no gas coming out of the injector. So I changed the fuel pump relay thinking it was bad and it didn't solve the problem. I don't know where to look anymore, what is the problem?
IP: Logged
PFF
System Bot
Patrick
Member
Posts: 31238
From: Vancouver, British Columbia, Canada
Registered: Apr 99


Feedback score: (1)
Leave feedback





Total ratings: 446
Rate this member

Report this Post08-03-2013 07:40 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by vladfiero:

I bypassed the relay to see if the pump was the problem but when I do I hear the pump running but even then there seems to be no gas coming out of the injector.


Obvious question - Do you have enough fuel in your tank?

Have you disconnected the fuel line to the throttle body to see if anything is actually being pumped? Have you checked to see if the fuel filter is plugged?

[This message has been edited by Patrick (edited 08-03-2013).]

IP: Logged
mike-ohio
Member
Posts: 742
From: Marion Ohio
Registered: Feb 2007


Feedback score: (1)
Leave feedback

Rate this member

Report this Post08-03-2013 08:54 PM Click Here to See the Profile for mike-ohioClick Here to visit mike-ohio's HomePageClick Here to Email mike-ohioSend a Private Message to mike-ohioEdit/Delete MessageReply w/QuoteDirect Link to This Post
Could be the piece of fuel line between the hard line and the pump split open.
Happened to me. Pump was fine but the line connecting it to the hard line split.
Either way you will be dropping the tank to replace.
I installed a new pump anyway while I had the tank out.
You have to use a special type of in-tank fuel line. Search function should locate it.
IP: Logged
James Bond 007
Member
Posts: 8779
From: California.U.S.A.
Registered: Dec 2002


Feedback score: (1)
Leave feedback





Total ratings: 263
Rate this member

Report this Post08-04-2013 10:49 AM Click Here to See the Profile for James Bond 007Send a Private Message to James Bond 007Edit/Delete MessageReply w/QuoteDirect Link to This Post
I agree with the posted recomendations....Allso the fuel pump may have poped off (I actualley had this happen).
IP: Logged
vladfiero
Member
Posts: 45
From: La Prarie, Quebec, Canada
Registered: Feb 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-04-2013 11:31 AM Click Here to See the Profile for vladfieroClick Here to Email vladfieroSend a Private Message to vladfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
so I dropped the tank this morning and the little piece of hose going from the hard line to the pump wasn't attached at all but I still don't get 12v when I turn the key?
IP: Logged
vladfiero
Member
Posts: 45
From: La Prarie, Quebec, Canada
Registered: Feb 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-04-2013 05:52 PM Click Here to See the Profile for vladfieroClick Here to Email vladfieroSend a Private Message to vladfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
after further testing and having changed the pump, the car wont start but I have found out the by jumping the injector to send gas into the tb the car starts and runs fine afterwards, it seems as if the signal for the injector to send the first pulse of gas is not happening could it be a temporary relay ?
IP: Logged
phonedawgz
Member
Posts: 17011
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post08-04-2013 07:45 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
The ECM is supposed to turn on the fuel pump relay by sending +12v on the Dk. Green/White wire. Use a 12v test probe and see if you are getting +12v for two seconds when you turn the key to on. You should also get the +12v if you bump the starter till two seconds till after the engine stops.

You are saying the engine is running fine if you start it on some gas otherwise right?

My guess is the fuel pump relay isn't turning on, most likely caused by a bad ECM. The oil pressure switch can ALSO turn on the fuel pump. But if your Fiero has lots of miles it might not build up enough oil pressure to turn on that switch unless the engine is running.

Test with the test light. If your ECM is poop, you can buy one from someone here on the Forum. Only 84 ECMs will work in your 84. Also if the donor ECM is from an auto and you have a stick or vice versa you will have to swap the PROM chips in them.

But test with your test light first before replacing the ECM.

[This message has been edited by phonedawgz (edited 08-04-2013).]

IP: Logged
James Bond 007
Member
Posts: 8779
From: California.U.S.A.
Registered: Dec 2002


Feedback score: (1)
Leave feedback





Total ratings: 263
Rate this member

Report this Post08-05-2013 11:31 AM Click Here to See the Profile for James Bond 007Send a Private Message to James Bond 007Edit/Delete MessageReply w/QuoteDirect Link to This Post
I have heard about water running down the fuel pump wireing harness and rusting out one of the pins (located on the rear firewall). If you can get it running,thats probubley not your problem. Do you hear the fuel pump relay click when you turn the key.

Allso when you installed the new fuel pump,I hope you used small metal hose clamps on that little hose that poped off.
IP: Logged
vladfiero
Member
Posts: 45
From: La Prarie, Quebec, Canada
Registered: Feb 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post08-05-2013 05:54 PM Click Here to See the Profile for vladfieroClick Here to Email vladfieroSend a Private Message to vladfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
when I was jumping the injector yesterday to start the car I had removed the relay before hand and had forgotten to plug it back, the car would start anyways and when I did notice and plugged it back there was no change, and no I do not hear the relay click when I turn the key and I did put metal clamps on the little rubber hose in the tank.

what else does the ecm control ? because I would think that other thing wouldn't work no ?

also beneath my fuel pump relay there are two other relays what are they for are they part of the fuel system as well? I do not have a/c

thanks
IP: Logged
benoitmalenfant
Member
Posts: 288
From: Chateauguay, QC, Canada
Registered: Sep 2011


Feedback score: (4)
Leave feedback

Rate this member

Report this Post08-05-2013 09:17 PM Click Here to See the Profile for benoitmalenfantSend a Private Message to benoitmalenfantEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by vladfiero:
also beneath my fuel pump relay there are two other relays what are they for are they part of the fuel system as well? I do not have a/c


I believe you're talking about the Turn Stop relay, nothing to do with the FuelPump.

------------------
Ben
87 GT / 88 GT
84 Indy #1863

IP: Logged
phonedawgz
Member
Posts: 17011
From: Green Bay, WI USA
Registered: Dec 2009


Feedback score:    (23)
Leave feedback





Total ratings: 290
Rate this member

Report this Post08-06-2013 12:17 AM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
There is a circuit on the ECM that runs the fuel pump relay control output. If you are not getting the +12v out of the ECM on the fuel pump relay activation lead then your ECM isn't sending the voltage on that lead. That would indicate a bad ECM.

The ECM also controls the injector, the ignition timing and the check engine light.

It is not unusual for an ECM to loose the fuel pump relay control circuit. The driver transistor that controls that output can fail and cause just the fuel pump relay to fail. But CHECK FIRST to see if the ECM is putting the voltage out on the Green/White wire that runs to the relay. You could have bad wiring. You could have a bad relay socket. You could have a bad relay. Or perhaps the ECM isn't putting the +12v out to the relay.

It all comes down to is if you are not getting the output on the correct pin.

84 Fiero uses the 1226156 ECM.

[This message has been edited by phonedawgz (edited 08-06-2013).]

IP: Logged
PFF
System Bot
vladfiero
Member
Posts: 45
From: La Prarie, Quebec, Canada
Registered: Feb 2013


Feedback score: N/A
Leave feedback

Rate this member

Report this Post10-23-2013 09:01 PM Click Here to See the Profile for vladfieroClick Here to Email vladfieroSend a Private Message to vladfieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
how do you change the ecm is it just plug and play?
IP: Logged

next newest topic | next oldest topic

All times are ET (US)

Post New Topic  Post A Reply
Hop to:

Contact Us | Back To Main Page

Advertizing on PFF | Fiero Parts Vendors
PFF Merchandise | Fiero Gallery | Ogre's Cave
Real-Time Chat | Fiero Related Auctions on eBay



Copyright (c) 1999, C. Pennock