Intermitant Computerized fuel pump control Problem
The computer on this car is not grounding the circuit to energize the fuel pump properly.. i checked the circuit and the PGMFI relay is good, At least the soldered jointed are good. I'm about to call A bad computer, But was wondering If anybody else had this problem and it was something else?
The only way I could get it to activate the fuel pump is by manually grounding that circuit. And I would think that when I did it would start and run BUT it doesn't!??. Only when the system grounds itself properly does it start and run. And it constantly has spark! I don't think it It is the relay but it might be. I cannot get it to activate by messing with anything!
Not saying its your problem but those ecu's fail quite a bit from the capacitors going bad and leaking out deteriorating everything around it. May be worth it to open it up and take a look .
Thanks Jason that I'm about to do! But why the heck doesn't it start when I manually operate the fuel pump? That's what gets me.
Are you sure the injectors are being enabled, anti-theft comes to mind. Just a thought
No I'm not, I will go there next. It was getting spark and the fuel pump was working but I'll bet that's why it didn't start because the injectors weren't activated. Would a bad PGMFI relay have something to do with the immobilizer? Or maybe It's the computer that's causing it.
Powers and grounds For ecm 5 volt reference circuits From ecm Distributer signals to ecm
You sure the relay is good? they used to fail all the time. I know low value input
Hi Doug, Pull the computer and open it up. I have had them invaded by ants before. Check the board for damage. Is this a SOHC VTEC or MFI? Check for a main power relay, it powers the fuel pump and the injectors. The main relay contains 2 individual relays.
Yeah something is wrong with this relay, it intermittentl clicks the fuel pump on and off I can get it started when it's activated but then it quits. I have ordered a relay on Amazon will be here in a couple days. Thanks
I can’t remember if this old of a Honda had the ground on the thermostat housing. Also I’ve had bad ECM cause a stall when cold. The after the ecm warmed up it would fire.
Checking a fuel pump you need to see a ground from the power wire to see a compete circuit.I think you have a bad pump.
No Intermittently it grounds to the computer advertising the pump. And I can also do that manually. But Thank you
Hey Doug the old Honda dealer check for that relay was in the driver seat, key it on if the relay does not produce a loud click at the exact time the check engine light turns off the car won't start. That old of a car now u may need to check few of the circuits involved just to be sure fuse 19 and 12 Come to mind.
I did check the powers and they seemed well. But I'll redo that on those fuses to make sure
It's most likely the relay itself but i have had issues with power side of it from after market alarms and what not slpiced in over the years
94 honda does NOT have immoblizer. Relay under dash, near steering column controls fuel and injectors. Large relay, brown color. Common failure.
Replaced the PGM-FI relay but the problem is still intermittent. The injectors haven't any signal when it happens but have power. I think the ECM is the problem. I'm going to open it up and investigate. Might a bad 5v ref somewhere be the culprit?
Well I take that back turns out he didn't contact me because he was getting another ride from somebody and didn't want to bother me! So I thought it was still okay but NOT! Funny thing is this customer has a 99 Mustang that I need to change the fuel pump on also! Sometimes it will activate the fuel pump and it will run but then after some time it won't and then i can't get it to do it again. No…
Hi Doug, They left you hanging Hmm…. taking you for granted and they are in denial? If they are avoiding the problem, there are two things that come to mind. One, they want an instant fix “shogun” repair. Two, they don't want to spend the money. I would move on and close this, then reopen with a new request.
Sorry I took so long to get back to the problem that was found. Customer hasn't needed the vehicle much but finally decided to have me replace the ECM that had a fried board. Here is a picture of it. Thanks.
Hi Doug, Glad you found the issue. Any idea what the root cause is? That looks like pretty significant damages to what appear to be power capacitors. Any history of a backwards jump start? if you still have the vehicle, look at the fuel injector connectors and harness, then Ohm the injectors. If anything, you have a record. Also look for aftermarket relays or any fuse box tampering. I get…
Hi Glenn, I really appreciate your giving me that information! No other circumstances that I know of but I will keep that in mind in case something more happens. Last year I did have to change the distributor on that because it had no spark but after that it ran well for a while. That is quite significant damage in those two places. And it's kind of odd to me that it would intermittently start…
“Any idea what the root cause is?” The caps are the root cause. They got old and leaked. Since the cap has lost its charge, their function in the circuit is going to be iffy, plus the leaked electrolyte is pretty corrosive to the copper so it eats it away which will cause over heating and there is also a lot of internal shorting happening because of the oxidation and corrosion it has caused…
Hi Jason thank you for that! Can you explain what you mean by caps I'd appreciate it. Thank you
Hi Doug, I'll chime in here and say “caps” mean capacitors in the electronic/electrical circuit. They are basically an electrical storage device to act as a buffer in many systems to absorb and dissipate sudden surges of power. They also provide stored capacity to supply sudden short demands has systems demand it under load. I have heard them referred to as “electrical energy shock…