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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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I think you found a new calling, Marcus.
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Posted on: 2013/8/18 16:03
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Ultraman | Re: 91 Corvette Convertible fuel pump issue | ||
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2015 Memorial Day Car Show Winner!
 
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Ha....ya it pisses me off when they put pumps where you can't get at them...they are going to fail and if you can't change them easily you're screwed.... Now I am doing research into if I can cut axcess holes into the floor of the storage areas in the GS. If I can, then I could access the top of the duel fuel tanks and pull the pumps and sensors right up out of the top without dropping the tank.....Tadge hasn't answered me yet....but I'm sure he will...  .....I think it can be done and reinforced so as not to mess with the integrity of the body structure....So why didn't GM do it.....who the hell knows...other then they want you to go to a chevy dealer and pay 3 large to have a sensor replaced while dropping the tranny and everything else on the backend....sonsabitches.... Oh man this is turning into a rant.....nevermind....  |
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Posted on: 2013/8/18 16:34
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2010 Grand Sport Coupe Gone but not forgotten... Vote DeSantis in 2024.... Make the IRS go away... |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
 
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I pulled the external fuel pump and it cranks with 12v applied. There are no mfg name markings but it has a stamp.
FP001(1?)-2 MFG DATE 053 12 VOLTS MAX PSI 125 It looks pretty much like this http://www.summitracing.com/parts/ATX-E8228/ |
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Posted on: 2013/8/19 18:06
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Attach file:  IMG_1267.JPG (68.66 KB) IMG_1269.JPG (58.16 KB) IMG_1270.JPG (60.16 KB) IMG_1271.JPG (50.03 KB) IMG_1272.JPG (50.58 KB) |
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Posted on: 2013/8/19 18:10
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Just because it works with 12v applied doesn't mean it can't quit when warmed up (I'm guessing). Guess I have to check the power from the relay but I might need an extra set of hands to turn the key on and off while I check it.
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Posted on: 2013/8/19 18:17
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Alrighty then. This is what I've found. The hot is hot the ground is grounding. I jumpered the red to the yellow and the pump fired. The green wire is now the main suspect. I believe the green wire goes to the ecm. The pump fired on 12v outside on testing. The pump fired when I jumpered the red and yellow. There are 4 wires at the relay. Black, red, yellow and green. The things I need to check are all related to the green wire. |
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Posted on: 2013/8/19 19:23
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| bogus | Re: 91 Corvette Convertible fuel pump issue | ||
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Grand Imperial Pooh-Bah
 
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that is not the stock relay.
I hate hack jobs... |
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Posted on: 2013/8/19 19:58
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| djxib | Re: 91 Corvette Convertible fuel pump issue | ||
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Senior Guru
 
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Guys,
I just saw this thread. I have an additional pump on my car, mounted behind the tag plate; I also have an aftermarket harness to drive the additional pump. Mine is all wired so that the 'stock' fuel pump supply drives the relay, and the relay drives 2 x separate pump feeds. The Power feed to the relay is hard wired to the alternator so the pumps get 13 volts rather than 12. The theory is that 2 pumps in series work only half as hard as one on it's own; I have a monster pump as my inline and it flows 80gph in my testing, enough (in theory) for 700 HP at 0.6 BSFC. FYI I mounted my aftermarket relay on the underside of the car, and the harness also came with some additional grounding lugs because the stock grounds for the pump are apparently not very good. Tommy - my aftermarket harness is made by Racetronix, I may be able to dig out the schematics this weekend if it would help. |
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Posted on: 2013/8/19 20:49
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Webmaster
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I doubt the green wire goes directly to the ecm. It probably goes to an aftermarket controller or your fuel pump power source for the main pump or something along those lines. Check that wire for continuity, it might have a break or loose connection.
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Posted on: 2013/8/19 21:23
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Followed the green wire . It connects to a gray wire that comes out of the tank then both connect to a gray wire from this harness by the fuel tank.
Attach file: IMG_1274.JPG (71.44 KB) |
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Posted on: 2013/8/19 23:08
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Thanks for your input, Andy.(djxib) It shed's a little light on the subject. The only kink in the armour right now seems linked to the green wire. Guess I'll pull the sending unit next to see what mysteries unravel. Maybe probe around that harness connection a little too.
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Posted on: 2013/8/19 23:22
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| 1Fast04Vert | Re: 91 Corvette Convertible fuel pump issue | ||
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Elite Guru
 
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That quick splice connector is well known for corrosion which results in a very poor connection. |
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Posted on: 2013/8/19 23:53
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| BillH | Re: 91 Corvette Convertible fuel pump issue | ||
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The Stig Moderator
 
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Especially since it's a 120v, and is supposed to be used for house wiring.,,,,,,,,,,,,,,,,Bubba. |
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Posted on: 2013/8/20 2:51
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Then maybe I should look for a circuit breaker.  |
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Posted on: 2013/8/20 3:00
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Webmaster
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I don't have a 91 fsm, just a 93. The 93 shows a gray power feed wire from the fuel pump relay. I'm assuming that's what yours is. In the 89 it's a tan/white(?) wire so not sure when the change was. I would test for power at that wire first. Also I would cut that quick splice out and solder it correctly as Andy mentioned above. I believe the purple and black are both for the fuel gauge. I could not find a direct wire listing in the FSM, they can be a PIA sometimes.
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Posted on: 2013/8/20 3:11
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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So what should the gray show? 12v? I have the 91 FSM. I'll take a look. Would that be plausible to have the green and red wire both running 12v to the Bubba relay? When it comes to auto electric I am The Weakest Link. I'm learning because I'm doing. I'll report my findings. |
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Posted on: 2013/8/20 3:20
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| BillH | Re: 91 Corvette Convertible fuel pump issue | ||
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The Stig Moderator
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There will be something in the FSM on how the F/P energizes, if you can't find it, let me know. It's possible that key-on, the gray wire only gets power for a few seconds before the ECM shuts off the power so, you'll have to get someone to turn the key while you watch the meter or have the meter where you can see it when you turn on the key. After the ECM turns off the pump, it will turn it back on when it sees injector pulses OR after cranking and getting oil pressure. |
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Posted on: 2013/8/20 3:34
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Every man dies but not every man lives. |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Thanks Bill (and Matt). I have some reading to do. |
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Posted on: 2013/8/20 3:37
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Webmaster
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The gray wire should be the power feed for the stock fuel pump. If the aftermarket pump is wired how I think, then it takes the reference signal from the gray wire to open the aftermarket relay. The aftermarket relay will have a ground, a constant power source, and a reference wire. The reference wire is what tells the relay to open and feed power directly from the battery (or constant power source) |
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Posted on: 2013/8/20 11:37
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Webmaster
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Quote:
Both the 89 and 93 manuals I have are crappy with their descriptions. The ecm does give the 2-3 second power application to the relay. There are orange and red wires responsible for signaling/powering the fuel pump relay. The gray wire is the power source from the relay to the pump. Once the ecm turns off the 2-3 second to the signal, there will be no more power to the gray wire unless you are cranking/running. |
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Posted on: 2013/8/20 11:40
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| bogus | Re: 91 Corvette Convertible fuel pump issue | ||
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Grand Imperial Pooh-Bah
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and that comes from the oil pressure switch... 4psi before it refires the fuel pump.
and that works in parallel with the fuel pump relay. a real mess... |
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Posted on: 2013/8/20 17:38
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Yep, they did something special. I went up under the passenger dash. The relays that the FSM said would be there are not there.  I moved some of the harnesses to peek around. I didn't see any relays. Looked like a bunch of harness connections. I guess that's one way to figure out your car. By looking. I hate messing with auto electric especially under the dash.I tested the fuel pump by jumping 12v at the harness back by the gas cap. Grey wire to the tank and branches to the external pump. It ran the external pump. Can't hear the inside pump since the outside one is so loud. I turned the key a couple of times and low and behold it started cycling and running. Doesn't mean anything is fixed it just means that it's starting and confusing the issue. Maybe I jostled some wires when I was under the passenger side. Anyway, it's running rough and acting like it's starving for fuel but it starts. I put everything back together and where I found it. It's not in the back. It's wiring, a relay, the ignition, a fuel filter, ecu, ccm or something else. I'm probably going to turn it over to my local GM trained, ASE qualified mechanic and see if he can make heads or tails of it.He has the tools, the testing equipment and the know how. He has his own shop. If he can fix it I'll have him give the whole car a good once over. There's a few issues that need t be addressed. Looks like it's the once every five years dump a couple (or few) grand into it to get it running right time. |
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Posted on: 2013/9/12 20:05
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Too bad you're not closer to one of us to look it over for ya. Good luck with the mechanic.
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Posted on: 2013/9/13 4:46
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_________________
2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Webmaster
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Results? Updates?
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Posted on: 2013/9/30 16:19
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Picked up the 91 at 04:00 PM. Defective coil, in tank fuel pump, sucked out the tank, oil pan gasket (leak), fuel filter, synthetic oil and oil filter. It's up and running. It still has an extensive list of items that need attention. Over time most of it will get done but now it's drivable. I asked the mechanic his confidence level that it would run good. He said "It's fixed". Drove it home. It starts crisply and seems to be running fine. |
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Posted on: 2013/10/10 2:02
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| Matatk | Re: 91 Corvette Convertible fuel pump issue | ||
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Glad it's done!
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Posted on: 2013/10/10 12:40
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_________________
2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| TommyT-Bone | Re: 91 Corvette Convertible fuel pump issue | ||
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Chair-man of the bored
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Just so you know, my total bill including tax was $718. Parts were around $242. Labor high 4's. I ain't complaining. I got my money's worth. 5 gals of gas etc. I've been too busy to mess with it lately. Besides. The coil being defective would have thrown me a curve ball. All is well. It's running.
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Posted on: 2013/10/10 20:36
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