I have 95 dx four door, with a really mysterious electrical issue. The problem is that the fuel pump will not turn on. I have checked and/or replaced the main relay, all the grounds (thermostat, valve cover to chassis, tranny to chassis), tried 3 different ecus, the under dash fuse box, ignition switch, fuel pump, and the wiring to the fuel pump. The car was an automatic that was converted to manual, but the swap was done properly. The car did actually start up and run for a few minutes before just dying out and not starting again. I did find that I had the wrong injectors on the engine (peak & holds, not saturated), so I thought I might have fried the first ecu. But changing the ecus did nothing. If I jump the main relay according to the Helms, there is voltage at the fuel pump connector. However, with the main relay (brand new one from Honda), the fuel pump will not prime. The CEL will stay on as long as the key is in the ON position. I, as well as two others (who are much more proficient with wiring/electronics) are just plain stumped. We have checked everything that we can according to the Helms. The only thing left would be to change the interior wiring harness, which I really don't want to do. Any help would be much appreciated.

Cliff Notes:
95 DX 1.5L
Fuel pump is not priming
Main relay, ignition switch, under dash fuse box, fuel pump, ecu, grounds checked and/or replaced
Jumping the Main Relay circuit as per the Helms manual results in voltage at the fuel pump plug, Main Relay is brand new from Honda
Fuses are good
Solid CEL
SRS light also stays on??
What else can I do?

 

have u tried checking the fuses under the hood...u might want to look at the ecu fuse..

 

bump for you. i need help. i might just wire my fuel pump to a switch and ill try and see if that turns on.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civicb16eg &raquo;</TD></TR><TR><TD CLASS="quote">have u tried checking the fuses under the hood...u might want to look at the ecu fuse..</TD></TR></TABLE>

Yeah, I've checked those fuses as well, all good.

 

just wire the fuel pump upto the ignition live it worked for me.

 

I got the CEL to turn off, turns out I did miss the ecu fuse. However, still not getting the fuel pump to turn on. I'd rather not wire it directly to the ignition...yet. I'd like to figure out what's really wrong.

 

The ECU uses the fuel pump control wire to engage a second set of contacts in the Main Relay. Is the ECU actually providing a ground on that wire when you turn the key 'on'?

If you jumped the Main Relay and the fuel pump turns on, then it doesn't sound like the Main Relay is being activated by the ECU.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">The ECU uses the fuel pump control wire to engage a second set of contacts in the Main Relay. Is the ECU actually providing a ground on that wire when you turn the key 'on'?

If you jumped the Main Relay and the fuel pump turns on, then it doesn't sound like the Main Relay is being activated by the ECU.</TD></TR></TABLE>

Thanks, that's what we suspected was going on. I'll have to check to see if it is indeed providing a ground.

 

sounds to me like the ignition switch might have a loose connection/wire pulling out, or just going bad. what you are saying is that there is no power to the pump when the key is initially turned on???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by schardbody &raquo;</TD></TR><TR><TD CLASS="quote">sounds to me like the ignition switch might have a loose connection/wire pulling out, or just going bad. what you are saying is that there is no power to the pump when the key is initially turned on???</TD></TR></TABLE>

I've replaced the ignition switch with a brand new one. Basically what is happening is that the main relay isn't getting the signal from the ecu to activate the fuel pump.

 

WOW I didnt think there would be anyone else with my exact same problem...thats crazy. Bump for some answers.

I guess you get more hits on a civic board cauz i got nothing.

here is my thread
https://honda-tech.com/zerothread?id=1571001


Modified by rluder21 at 9:59 PM 3/25/2006

 

Seems like it's season for this problem. There are a few others that have/had this issue too.

 

how much gas do u have in your tank?

 

I have about a 1/3 of the tank. It's been pretty much narrowed down to a wiring issue. I'm going to swap out the engine harness first, and see what that does. If not, I'll know it's within the interior harness.

 

The shotgun approach to solving problems gets expensive real quick...

A multimeter and a Helms are really needed here.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">The shotgun approach to solving problems gets expensive real quick...

A multimeter and a Helms are really needed here.</TD></TR></TABLE>

Unfortunately, I've learned this the hard way. I probably really did not need to get all the replacement parts that I did. So basically, I'm back where I started, with the aforementioned multimeter and factory manual/electrical troubleshooting manual.

 

So when you turn the key 'on', is the ECU actually getting power then?

 

how do you test if the ECU is getting power or not? Since the ECU powers the fuel pump, I would think to test if the ECU is getting power first, but how do you test that?

 

You just use a multimeter. You need to know which pins on the ECU are the power supply pins. When you initially turn the key 'on', you're first getting power to the ECU. The ECU then in turn supplies a ground signal to a second set of contacts in the main relay, which is responsible for turning on the fuel pump.



A11 & A24 are the power inputs.

 

Well...I'm officially an idiot! Turns out after going through the entire process in the Helms manual it was some stupid 7.5 amp fuse in the fuse box under the dash. Check all your fuses not just by eye either, take them out. I thought mine were okay until the Helms manual told me to check it. I would have to say that the Helms manual OWNS all!!!

 

What i did was ground off the ground wire for the ecu to a different ground and it fired right up. The grounds might be bad. I replaced my grounds espeically the one on the thermostat and made an extra gruond for the ecu ground wire. Hope this helps

 

I'll give it a shot.