SoCalManche

Yup, ECU back in truck. So is it bad that I'm 4V over for MAP and TPS?

MAP sensor: A - 0 Volts / C - 9 Volts TPS sensor: A - 3.65 Volts / C - 9 Volts

Yes, I know the MAP is on the firewall; TPS is what I forgot. So I'm testing for volts, not ohms? I was back-probing the middle (B) wire on the three-wire connectors and it was going blank, versus the O2 sensor reading properly. If I'm to test for volts instead, which wire? A?

Looking to pick your guys' brains. Did some back-probing on some connectors to try to locate where the issue is occurring. I'm having an issue with my multimeter maybe? When I test the O2 sensor connector, it reads 0.5-0.6, so not too shabby. However, when I try to test the MAP sensor connector or the other one ( can't think of the name currently) that connects directly into the TBI, the reading goes from 1 to blank. No 0, just blank like it shuts off. What's up with that? (Electrical diagnostics is not my strong suit) Also, I checked the resistance at the fuel pump connector, and it is reading 0.5 ohms as well. When I was checked the D1 connections: - D1_5 reads battery voltage - D1_2 reads 12 volts - D1_6 reads 2-something volts when relay is in the circuit; D1_6 reads 12 volts when fused jumper wire is inserted between pins 87 and 30. That's all I can think of at the moment. Thanks for any and all input thrown my way.

Reviving this thread to understand what exactly I'm looking at here. It's cool looking.

Yes, initially threw a new relay in and same issue persists. Actually, when I would swap out the new one and put the old relay back in, I remember it would start ticking sometimes? Just the old one though; the new one never ticked. The only way the fuel pump would turn on is by a fused jumper wire. That is still true today, as I've been messing with it for the last couple days now.

Good to know! Thanks for the info! Will do. Headed down the rabbit hole now. Thanks.

I tried to pull the board out but it didn't seem to want to budge...I didn't pry any harder because I didn't want to end up breaking the damn thing. As for why I was hoping something was fried....long story short I posted on here a year ago, trying to get my 'Manche up and running and I could not find the issue. It died on me while I was driving it because I ran out of fuel, and when I threw more in it, it would not start. After that: - Engine would fire with fuel added directly to throttle body - Fuel pump wouldn't prime when ignition was switched to ON - Fuel pump would engage with a fused jumper wire in place of relay - All grounds had been refreshed per Cruiser's Tips - Added a few grounds where Cruiser recommends within the engine bay I've seen in other posts that the ECU can be the cause of this issue that other members have had like this.

I pulled out my ECM hoping to find visible, fried components inside, but from the looks of it, that does not seem to be the case. I'm pretty novice when it comes to testing electrical issues, so can someone tell me the appropriate way of testing the ECM to verify it is properly working? Thanks!

So a new development has occurred. Since leaving the truck overnight once again, I came back to recreate the constant clicking from the original relay I had for the fuel pump. I was unable to recreate the constant clicking. Whether using a new relay or the old, original one, I could not get the relay to click constantly, with or without the fuel pump connected. I have no idea what this means. I also tested all the fusible links downwind one by one and they all had 12.4-5 volts of juice flowing through. Now engine will not fire at all, just constantly turn over. Jumper wire still starts the fuel pump continually while the relays will not. Will be checking fuel pressure later when returning to the 'manche. As far as wet fouling is concerned, I think these look bad, but a fellow associate of mine said they look fine. I disagree? (Did not take out #1 due to the hassle it would take to get to it)

I don't know what you want me to tell you, man. I replied to his specific question. I held the key at START, and the only time the engine will actually FIRE is when there is fuel in the throttle body. You can hear the starter engaging in full force before it FIRES and then dies off in a couple seconds. If no fuel is added, or the jumper wire is in the relay terminal even though it turns on the fuel pump, the starter will continue to "turn over" without firing. I apologize for semantics getting in the way of a solution.

I'm looking to bump this thread, because I had the same issue, but with an extra issue. My fuel delivery is messed up too, but it's not due to the rubber hose on the pump itself inside the tank. I replaced the hose there, as well as checked the fuel filter to make sure it's free-flowing (which it is), and when the fuel pump is engaged, it sounds like it is feeding into the throttle body. Here's the issue: I have to use a jumper wire on the fuel pump relay socket to get the fuel pump to engage on its own. The main ground for the pump is super shiny and clean, but when I have the original relay in the socket, it just constantly clicks, and when I have a new relay in the socket, nothing happens at all. The only way the fuel pump primes is by a fused jumper cable from pin 30 to pin 87. At first, when the original relay was in the relay socket, I could pour fuel into the throttle body, and it would start up like a champ, only to die after the fuel had been burned off. Now, it's starting to struggle to even do that with the original relay in. With the jumper cable priming the fuel tank, the engine will not fire at all. It will constantly try to crank, but it will not fire for some reason. I have not tried the fuel pressure yet, but that is on my list for the next time I see my truck. Also may check spark plugs to see if they got fuel-logged from the fuel pump constantly priming before cutting it off. If anyone has any words of wisdom, I'm all ears. I've been trying to remedy the problem for four days...

Hmm...I don't recall if I had the ignition ON when I looked down the TBI with jumper attached to relay. But if you say I would know when I saw it, I did not see much even though I could hear and smell it. That's concerning.

Noted. I will test this tomorrow as well as a fuel pressure test. On a different note, I have a question. I can smell and hear fuel flowing to the TBI (when connected to fused jumper wire), but do not necessarily see it. Am I supposed to be able to see it?

Yes. When I replaced the fuel line retainer clips, fuel would leak out when pump started. To remedy this, I bought fuel line o-rings, put one up there, and the leak subsided. So with the question of the pump working or needing a new one, I saw it working in action, while also hearing it turn on with the jumper. But to reiterate, there is no fuel leak any longer, nor has there been for a bit now.

Fuel filter is clean. Took it out and verified.

I got a new pump orginally, which by the way isn't properly spec'd out for these trucks. But regardless, I took the original pump out, tested it at the battery, and it immediately started. Whenever I connect the jumper wire in the fuel pump relay, it immediate comes on. And it is definitely pushing fuel, because one of my fuel line retainer clips broke, and the new ones you buy need o-rings. I didn't know that, and so as soon as the jumper wire engaged between 30 and 87, fuel started coming out of the fuel lines at the connectors underneath the intake.

No, it didn't.

Also, now when I try to start with the original relay connected, the engine struggles to start with fuel added to TBI, and when it does, a popping noise occurs around the intake/TBI and it shuts off abruptly.

No. With jumper wire connected, fuel pump constantly primes but no start. With original relay connected, no priming but will start with fuel added to TBI. Help...lol...

Would there be a reason as to why the original relay clicks repeatedly when a new relay won't?

That worked to engage fuel pump via 15A fused jumper wire. Too much fuel entered the intake, so waiting a few minutes before trying to start again. Will come back with reading. What does this mean for now?

Does it matter what size fuse to put in the jump wire?

Gotcha. I have to run and grab a jumper.

D1_5: 12.5 volts D1_2: 10.6-10.7 volts D1_6: 1.8 volts