2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Fuel pump electrical problem

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Old Jul 30, 2007 | 11:44 AM
  #1  
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srr
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Fuel pump electrical problem

I have an '88 TII, and I was out tooling up and down the road for the first time since RTEK-ing it when the engine just went braaaaaaaaaaaaap and stopped. It would turn over, but not start.

After dragging it home, we found we had no fuel pressure, and we also noticed that the black/white and blue/white wires from the 4-wire connector to the egi main relay were VERY toasty, to the point that insulation was melting, and the main 30A egi fuse was very hot as well, but not blown. We replaced the fuel pump, and it whirs when the key's turned on with the terminals of the yellow, two-pin check connector bridged (as per Haynes' "fuel pump operational check"), but the wires and fuse still get HOT. The wires and fuse heat up when the key is turned on whether the pump is connected or not.

Any specific suggestions, other than "it sounds electrical"?

Also, what resistance should I measure across the fuel pump motor windings, and is an 88 TII fuel pump the same as an 88 NA fuel pump?

Thanks,
Steve
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Old Jul 30, 2007 | 06:37 PM
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From: home of the Airborne, NC
do the fuel pump rewire. you'll be happy you did it once your done. there are a bunch of write ups on how to do it.
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Old Jul 30, 2007 | 07:02 PM
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I really don't think that is it. The problem is, we don't have any good wiring diagrams for the car. Can someone tell me what the 2 check connectors that are near the solenoid block are? There is a yellow, green, and white one. The yellow one goes to the EGR solenoid, what are the other 2 that are not connected to anything?

Thanks!
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Old Jul 30, 2007 | 08:54 PM
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From: Eldersburg MD
This is all on a 1988 TII motor swapped into a 1988 convertible BTW. The fuel pump and EGI fuse/relay wiring is all the stock 88 vert. body harness.


I have the ECU out of the car, and also the main solenoid and injector opening relay out of the car.

The Black/White and Black/Yellow wires of the 4 pin connector have continuity. I do not think that this is not right.
The white/blue and black/white (in and out for the switch IIRC) are the ones getting very hot. It also seems that every wire of the 4P connector is being grounded.
For whatever reason, this also seemed to cause the fuel pump to die (read no resistance).

My question is, somewhere along the path, do the wires meet somewhere else, possibly in another relay or sensor somewhere, that could be shorting them to ground?
and
How does the fuel pump dying tie in to this electrical nightmare in a way that makes sense?

Last edited by robboser; Jul 30, 2007 at 09:08 PM.
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Old Jul 30, 2007 | 09:13 PM
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the fsm is available for free download in several places, they are listed in the 2nd gen faq in this section. that has all the wiring diagrams you could ever want.

pat
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Old Jul 30, 2007 | 09:58 PM
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For a "Resident Know-it-all" you sure are being a resident "waste of a post."
I've noticed that a lot of people on the RX-7 forums look down upon people who are trying their best to fix something themselves without having to take their car to a shop, and just might not have all the skills, equipment, knowledge, or experience to do so. When someone turns to the forum for help and you do not have any to offer, please do not offer a useless "general knowledge" post.
My understanding of forums is that they are supposed to be here as backup when in need and a place to discuss our cars. You are not promoting a sense of community, and I am sorry that there are people like you on this forum who exude an aura of knowledge yet seem so unwilling to lend a hand to fellow forum members in need.
I am not an idiot. We are just going through the wiring diagrams trying to figure things out. We have been tracing the wires using a Haynes manual (which for those of you who don't know, has some very anemic diagrams that are poorly laid out), and we were just wondering if there has ever been anyone out there with a similar problem who could save us a little bit of time trying to decipher our PDF scanned wiring manuals (not to mention having to print out multiple sheets and tape them together), and possibly shed some light as to why this happened in the first place, when the car was running great for 20 minutes following the install of a new Rtek 1.7 ECU/720 CC injectors/Walbro Fuel pump, and then just decided to take a dump on us for seemingly no particular reason.

Its really a shame that you do not have something more substantial to contribute.

Thanks a lot.

Rob

Last edited by robboser; Jul 30, 2007 at 10:06 PM. Reason: more to say!
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Old Jul 30, 2007 | 10:24 PM
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wow Patman, that was a pointless *** response.

Hopefully you can find it and don't have to rip up all the wiring. That's a whole separate harness. Keep us posted if you figure it out, SOME OF US might actually like to know what to do if this ever happens to us, instead of just closing our minds and opening our wallets to a shop.
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Old Jul 31, 2007 | 12:19 AM
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So? Why don't you download the free wiring diagrams? How can you say you don't have good wiring diagrams for the car when they're free and available online?

The power enters the Main Relay on a BW wire. . That relay closes and the power leaves the Main Relay on a Blue wire which is a part of the FRONT harness. Then the bluewire (L) mates with the Rear harness at a connector called FR-02 (Front to Rear) and arrives at a connector under the carpet on the backside of the left rear strut tower. There it mates with the fuel pumps pigtail harness and now becomes a black/white wire the rest of the way to the pump itself.

The free, online FSM wiring diagrams show this for a series four car. Non turboii car and also the TurboII car. Yours isn't turbo car and is a turbo engine in a non turbo chassis. So the following pages apply.

Page 50-36 of the free, online wiring diagrams for a series four non turbo car. It also shows the locations for the plugs in a general sort of way.

I used to jpg and post the pages out of the FSM until I realized how foolish that is.

Haynes manuals have their place in life. Like acting as a coaster for a frosty beer. That's 'bout all though. Their wiring diagrams have too many differnt models depicted.

Last edited by HAILERS; Jul 31, 2007 at 12:28 AM.
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Old Jul 31, 2007 | 05:37 AM
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We already went and dug out our manual on CD last night. As stated before, we were just wondering if anyone could save us some time and point us in the right direction, and also whether anyone has had a failure like this before, and how it happened.

This way we can avoid what happened last time and make sure everything is perfrect.
We have no idea whether this was a result of the ECU, Fuel pump, or another failure.

Thank you for the info though.

Last edited by robboser; Jul 31, 2007 at 05:46 AM.
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Old Jul 31, 2007 | 12:07 PM
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From: FORT WORTH, TEXAS,USA
Originally Posted by robboser
I really don't think that is it. The problem is, we don't have any good wiring diagrams for the car. Can someone tell me what the 2 check connectors that are near the solenoid block are? There is a yellow, green, and white one. The yellow one goes to the EGR solenoid, what are the other 2 that are not connected to anything?

Thanks!
Something is goofball here. There is no White plug/solenoid on a series four. On a series Five non turbo there is a White for the VDI. No VDI on a series four na.

There should be a Blue for the Relief solenoid.

A grey for the Switching solenoid.

Orange for the FPR

Yellow for EGR.

Green for Twin Scroll on a series four turbo

Is this solenoid rack off a series four turbo or non turbo car?
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Old Jul 31, 2007 | 12:08 PM
  #11  
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There's non Fuel Pump Rewire to be done if this is a series four non turbo chassis.
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Old Jul 31, 2007 | 12:18 PM
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The Blue/White wire at the Main Relay comes from the thirty amp fuse. The Main Relay closes and the Blue/White now becomes a Black/White output wire that feeds every solenoid on the rack. Notice how EACH solenoid plug has a black/white wire. The black/white wire also goes to the ACV's two solenoids.

It sounds like you have a short on one of the black/white wires on a solenoid. Which one? Got me. I'd go to the ACV and look at the wires on the two solenoids there.

So now you should have a clue about why the black/white and White/Blue wires are hot. NOTHING to do with the fuel pump.

I described how the fuel pump is fed in a post above. NOT the same black/white wire at all.

OH. How did you wire the engine in the chassis????? Did you use the TURBO EM harness on that na car????? That is an important clue to your problems.
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Old Jul 31, 2007 | 12:34 PM
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From: FORT WORTH, TEXAS,USA
****
The Black/White and Black/Yellow wires of the 4 pin connector have continuity. I do not think that this is not right.
************************************************** *************
No. That is normal. Those wires go to solenoids/items that have gnds on their other ends. Not a problem at all. Normal.

What harness is on the engine? Turbo or non turbo? And this is NOT a fuel pump problem.
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Old Jul 31, 2007 | 12:40 PM
  #14  
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From: FORT WORTH, TEXAS,USA
That black/white wire at the Main Relay feeds the items mentioned above plus the over the top or fifth gear switch. Try this. With everything connected, turn the key to On. Then put the transmission in fifth gear for a minute or two and see if the EGI fuse blows or not. Just a possibility.
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Old Jul 31, 2007 | 09:48 PM
  #15  
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From: Eldersburg MD
We used the turbo engine harness on the NA car. Everything has been running perfect for over a year. As you said, we have come to the conclusion that there might be a short at one of the solenoids, possibly the Air bypass solenoid.
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Old Jul 31, 2007 | 10:43 PM
  #16  
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I found the problem. The air supply valve solenoid valve was shorted out and drawing way too much current through the whole system. Thank you for offering your assistance HAILERS. Its nice to see that there are still a few people that can offer help without giving too much crap.


Now we just have to cross our fingers and hope the ECU is still intact, and locate a new fuel pump and ASV valve.
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Old Aug 1, 2007 | 08:07 AM
  #17  
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HAILERS
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From: FORT WORTH, TEXAS,USA
The Air Supply Valve is used when pwr steering is used. No pwr steering....no need for the valve. That's the one on the back of the throttle body facing the firewall.

ECU should not be hurt at all. Even though the same black/white wire also feeds pin 3I on the ECU. If memory serves, the car will run without that pwr on 3I of the ECU.

I trust you took care of the miswiring b/t the plugs on the Turbo EM harness that interface with the Front harness. Those plugs are called FEM-01 and FEM-02 on the diagrams, sometimes called X-15 and X-16 on early cars. If nothing is done, then you have the boost sensor input to the ECU compromised.
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Old Aug 1, 2007 | 05:18 PM
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From: Eldersburg MD
We did the full swap and made the necessary changes to the harness to run the TII motor in the vert body
We've had the swap in for about a year and a half, and the car had been running great, but developed some misfiring under boost due to broken wires and bad grounds. We fixed all that up when we took up the manifold to put in the larger injectors. I guess it was just time for the ASV to go. Sucks that it happened like this though, 15 minutes after we got the car running. It was running like a dream too.


Thanks!
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