Fuel system question

New2Me87GN · 10-04-2006, 03:27 PM

On my 87 GN the prevous owner installed 2 fuel fumps (outside the tank) and did away with the 1 in the tank (not sure on his reasoning). He added another 3/8 line through the sending unit into the tank and the car now has 2 fuel lines going from the tank. Each fuel pump is hooked to a seperate line and after some tracing of the lines I found out that each fuel line is plumbed to each side of the fuel rail (seperate pump for each side). 1 pump is wired to the stock power source and the other pump gets power from a wire that I haven't found the other end of yet

, but if they both are running the car dies.
Now this car has been sitting for the last 12 years and it had a full tank of stale gas and I finally got everything cleaned up and new gas and new filters installed. My questions are why 2 pumps ran like they are and where do I check to see why the stock fuel pump power wire dosn't have power (I already checked the fuse)

J Banning · 10-04-2006, 04:55 PM

Why is it like that?

Well, back in the day many people ran an external fuel pump. I had one on my car when I got it. I've even heard of guys running four (4) pumps! That was a long time ago though.

evenfire6 · 10-04-2006, 06:02 PM

very old school, i actually seen a guy still using a seventh fuel injector...

New2Me87GN · 10-04-2006, 06:39 PM

Old school, maybe cause its been in storage for the last 12 years, I finally got it running, but it runs awfully ruff and the rear main leaks (not unusual), Man these cars are complicated

I traded a 1980 Camaro (with a BBC)that I built for it
http://video.google.com/videoplay?do...88104413933291
http://video.google.com/videoplay?do...55367783373438

Just a Six?? · 10-04-2006, 07:11 PM

These cars can be a little weird when they are new to you but with some patience, basic mechanical knowledge/tools & some extra $$ you will be amazed at what these 20 year old v-6s will do! Nothing short of amazing! BUT reading is mandatory along with asking questions! Good Luck & Have Fun!!

Black Car · 10-05-2006, 11:49 AM

Everone inplied that it was old school, which it is but if the pumps are still up to snuff will work.
In the late 80s & early 90s, there was no higher volumn and higher pressure replacement in tank pumps for these cars. The factory pump ( in most cases) couldn't supply enough fuel to support very low 12s without going lean.
Then the main way to get more volumn and pressure was to use two external pumps, usually Bosch brand.
Some ran a hose to each side of the fuel rail and some to just the one side.
In 92, I added another suction line to my car gas tank and mounted a Bosch 15 amp external pump. This was tee into one line and ran into the fuel rail.
the second pump was wired with an adjustable pressure switch (& manual) to
to supply additional fuel when needed. It still works great.

Now there are reliable dual intake pumps that do the same job. Usually the second pump is on an adjustable pressure switch because the extra fuel isn't needed at idle or low boost(+/- 15#) conditions.

Gary

New2Me87GN · 10-05-2006, 08:01 PM

Thanks for the insite guys. I have another question that I am not finding the answer to anywhere.
Here goes. The 1 fuel pump that is hooked to the stock sending unit wire does not turn on when the key is turned, but turnes on when I hook the grey wire behind the alt to the + post on the alt. Now I found this on Steve Woods site

Quote:

The oil pressure sender provides a back up to the fuel pump relay. When the oil pressure rises to four psi when the engine is being cranked, the contacts in one side of the sender close and send power to the pump. This allows the car to start even if the relay has failed although it will take more cranking before the pump is energized.

,
and my car won't start no matter how long I crank on it, but if I hook 12 volt to the pump the car will start right up. So what am I missing?

richie6 · 10-05-2006, 08:33 PM

That Camaro is wicked!

You'll have days when you wish you kept it.

ngtfd · 10-05-2006, 11:40 PM

does the car have the stock fuel pressure regulator, or was it upgraded
to an adjustable regulator?

V8 EATR · 10-06-2006, 12:17 AM

Gee Gary that fuel system sounds kind of like mine. Have had mine since new,'87, and you are right about the lack of hi-po/ hi pressure pumps. I have 2 externals, I think they were for a turbo 930. Been so long I cant remember. Anyway, I have 2 pickups in the the tank and ran 2 lines all the way to the eng compartment into a y where it went to 5/8" (same size as the rubber nozzle line at the gas station) up to the fuel rail. The rail was modified with an AN fitting and it was all covered in the black wiring loom material and you cant even tell its there. Been on jackstands since the Buick Nats in '93. Actually it has been out twice since then( for a total of about 50 miles!!) but I try to start once a month and go vroom vroom in the garage. With all the help available on here I am getting excited about getting it back out!!!! Wow that was long winded,sorry all !!!!!

New2Me87GN · 10-06-2006, 09:03 AM

Quote:

Originally Posted by ngtfd

does the car have the stock fuel pressure regulator, or was it upgraded
to an adjustable regulator?

Stock pressure reg.

Black Car · 10-06-2006, 10:53 AM

Quote:

Originally Posted by New2Me87GN

Thanks for the insite guys. I have another question that I am not finding the answer to anywhere.
Here goes. The 1 fuel pump that is hooked to the stock sending unit wire does not turn on when the key is turned, but turnes on when I hook the grey wire behind the alt to the + post on the alt. Now I found this on Steve Woods site
,
and my car won't start no matter how long I crank on it, but if I hook 12 volt to the pump the car will start right up. So what am I missing?

A simple answer maybe a secret fuel shutoff switch or fp relay is bad.

Gary

New2Me87GN · 10-06-2006, 07:12 PM

Quote:

Originally Posted by Black Car

A simple answer maybe a secret fuel shutoff switch or fp relay is bad.

Gary

Secret fuel shut off

??? Where would that be? Is there a way to tell if the FP relay is good or bad? (yeah, yeah use the search right)

xxxturbo6 · 10-07-2006, 09:03 PM

Quote:

Originally Posted by New2Me87GN

Secret fuel shut off

??? Where would that be? Is there a way to tell if the FP relay is good or bad? (yeah, yeah use the search right)

If your fuel press relay is bad!, it should still start! I just went through this test myself. I took the fuel relay completely out and the car still started up. it took more turn overs but it started. See, The fuel relay is run in series with the oil press relay so when your turning the car over and the engine builds oil press then it will start. If I was you! i'd look at the orange wire coming off your battery ( ECM wire ) disconect it at the disconect, take a multi-meter and see if the small section of wire from the batt ohms out cause the wire has a in-line fusable link in it and right at the end of it is where mine went bad! I went and got another wire with a 20amp in-line fuse and spliced it in and it cost $5.00 to fix. Your ECM is not giving out the voltage but when you manualy do it, it works. then your problem is NOT the pumps or relays it has to do with what the computer is telling it to do.. Scot w.

New2Me87GN · 10-07-2006, 09:11 PM

Ok so I finally firgred out the fuel pump deal, it was a fuse after all (I was testing the wrong fuse the other day) now I feel kinda stupid.
On my second pump I figured that out as well (well almost) they have it wired to a relay that gets power from the fuse box in a spot marked IGN, and 1 wire is a ground, and 1 wire goes back to the pump and the other wire goes inside the car and under the dash and has been cut. Now I can't seem to figure out what they had this wire hooked to? It must have been something that failed cause the whole length of it from under the dash to the relay is melted and f'ed up. Any guesses on what they may have had this second pump hooked to?

10-04-2006, 03:27 PM	#1 (permalink)
New2Me87GN Registered User Join Date: Sep 2006 Location: upstate NY Posts: 30	Fuel system question On my 87 GN the prevous owner installed 2 fuel fumps (outside the tank) and did away with the 1 in the tank (not sure on his reasoning). He added another 3/8 line through the sending unit into the tank and the car now has 2 fuel lines going from the tank. Each fuel pump is hooked to a seperate line and after some tracing of the lines I found out that each fuel line is plumbed to each side of the fuel rail (seperate pump for each side). 1 pump is wired to the stock power source and the other pump gets power from a wire that I haven't found the other end of yet , but if they both are running the car dies. Now this car has been sitting for the last 12 years and it had a full tank of stale gas and I finally got everything cleaned up and new gas and new filters installed. My questions are why 2 pumps ran like they are and where do I check to see why the stock fuel pump power wire dosn't have power (I already checked the fuse)

10-04-2006, 04:55 PM	#2 (permalink)
J Banning Alcohaulin' Join Date: Sep 2001 Location: Wilmington, DE Posts: 5,844	Why is it like that? Well, back in the day many people ran an external fuel pump. I had one on my car when I got it. I've even heard of guys running four (4) pumps! That was a long time ago though. __________________ Banning Cohen 1986 T-Type WH1 10.62@125.45 (1.43 best 60') Mid-Atlantic Grand National Association (MAGNA) Club Director & Delaware State Rep. Sign up for the 2008 MAGNA Points Series Mods: New combo in the works -- 109 block, big turbo, Michael's TH400 w/brake

10-04-2006, 07:11 PM	#5 (permalink)
Just a Six?? I Buried Beachbum Here! Join Date: Jun 2003 Location: Toronto Posts: 10,812	These cars can be a little weird when they are new to you but with some patience, basic mechanical knowledge/tools & some extra $$ you will be amazed at what these 20 year old v-6s will do! Nothing short of amazing! BUT reading is mandatory along with asking questions! Good Luck & Have Fun!! __________________ 87 LTD. Purchased May 88 Doeskin leather, coach lites, moonroof & carpeted trunk. No Factory Hood Ornament! Special order by the VP of GM Canada! Not another like it! Lots of Go Fast goodies! 11.5 is as Fast as I go! Thats what the track told me! It's a Small World, but I wouldn't want to Paint It!!

10-05-2006, 08:33 PM	#8 (permalink)
richie6 Irish Mick Join Date: Aug 2002 Location: Nanaimo B.C. Posts: 1,320	That Camaro is wicked! You'll have days when you wish you kept it. __________________ 87 GN T-roof car. Bone freakin' stock original engine w/ 20k miles. Stock Turbo. Stock injectors. 10 yr old XP pump. Art Carr 9" 3500 non l/u, Art Carr shift kit. 90/10 & 50/50's. Waiting to build the Mother of all 109's. 1987 Park Ave T-Type 1994 Chev Silverado 1976 Barth 28' P30 454

10-05-2006, 11:40 PM	#9 (permalink)
ngtfd ngtfd Join Date: May 2005 Location: Seattle Posts: 56	fuel pumps does the car have the stock fuel pressure regulator, or was it upgraded to an adjustable regulator? __________________ Doug

10-04-2006, 06:02 PM	#3 (permalink)
evenfire6 Registered User Join Date: Jun 2006 Location: northern indiana Posts: 91	very old school, i actually seen a guy still using a seventh fuel injector...

10-04-2006, 06:39 PM	#4 (permalink)
New2Me87GN Registered User Join Date: Sep 2006 Location: upstate NY Posts: 30	Old school, maybe cause its been in storage for the last 12 years, I finally got it running, but it runs awfully ruff and the rear main leaks (not unusual), Man these cars are complicated I traded a 1980 Camaro (with a BBC)that I built for it http://video.google.com/videoplay?do...88104413933291 http://video.google.com/videoplay?do...55367783373438

10-05-2006, 11:49 AM	#6 (permalink)
Black Car Registered User Join Date: Oct 2000 Location: Raleigh, NC Posts: 106	Everone inplied that it was old school, which it is but if the pumps are still up to snuff will work. In the late 80s & early 90s, there was no higher volumn and higher pressure replacement in tank pumps for these cars. The factory pump ( in most cases) couldn't supply enough fuel to support very low 12s without going lean. Then the main way to get more volumn and pressure was to use two external pumps, usually Bosch brand. Some ran a hose to each side of the fuel rail and some to just the one side. In 92, I added another suction line to my car gas tank and mounted a Bosch 15 amp external pump. This was tee into one line and ran into the fuel rail. the second pump was wired with an adjustable pressure switch (& manual) to to supply additional fuel when needed. It still works great. Now there are reliable dual intake pumps that do the same job. Usually the second pump is on an adjustable pressure switch because the extra fuel isn't needed at idle or low boost(+/- 15#) conditions. Gary

10-06-2006, 12:17 AM	#10 (permalink)
V8 EATR Registered User Join Date: Mar 2006 Posts: 11	Gee Gary that fuel system sounds kind of like mine. Have had mine since new,'87, and you are right about the lack of hi-po/ hi pressure pumps. I have 2 externals, I think they were for a turbo 930. Been so long I cant remember. Anyway, I have 2 pickups in the the tank and ran 2 lines all the way to the eng compartment into a y where it went to 5/8" (same size as the rubber nozzle line at the gas station) up to the fuel rail. The rail was modified with an AN fitting and it was all covered in the black wiring loom material and you cant even tell its there. Been on jackstands since the Buick Nats in '93. Actually it has been out twice since then( for a total of about 50 miles!!) but I try to start once a month and go vroom vroom in the garage. With all the help available on here I am getting excited about getting it back out!!!! Wow that was long winded,sorry all !!!!!

10-07-2006, 09:11 PM	#15 (permalink)
New2Me87GN Registered User Join Date: Sep 2006 Location: upstate NY Posts: 30	Ok so I finally firgred out the fuel pump deal, it was a fuse after all (I was testing the wrong fuse the other day) now I feel kinda stupid. On my second pump I figured that out as well (well almost) they have it wired to a relay that gets power from the fuse box in a spot marked IGN, and 1 wire is a ground, and 1 wire goes back to the pump and the other wire goes inside the car and under the dash and has been cut. Now I can't seem to figure out what they had this wire hooked to? It must have been something that failed cause the whole length of it from under the dash to the relay is melted and f'ed up. Any guesses on what they may have had this second pump hooked to?

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