TBI fuel pump voltage

[mike gw]

Alright, so I just got the ebl "ecm" which is very cool, (unless it is what is causing my problem, then it is a piece of ****.) I was on a little drive, to do some tuning. I stopped to make an adjustment to the trans linkage. (you 727 guys know what i am talking about!) It would not re-start...
I noticed on my laptop, when you first cycle the key, the fuel pump gets 12 volts. Then it shuts off (normal) and volts go to zero. When cranking volts are still at zero. I couldn't hear the fuel pump,
I swapped it out, with a spare. (made access hole when I put in bronco tank) so it only takes about 6 min.
Same problem, I have a gauge mounted behind tbi, I noticed when I cycled the key I was still not getting fuel pressure. I could hear the pump running. I took off the feed line from tank and cycled the key to see if there was fuel, none. I sat in the parking lot perplexed, then decided to reverse the wires on the fuel pump. I did that and fuel came out. Hooked everything back up, and still no volts to fuel pump while cranking. Did a cursery check of wiring, and it seems OK...
Any thoughts...

I have no idea what I did to this jeep to piss it off, but he has been fighting me like I crashed his mama into a tree.

I think the one word to describe gw owners is "persistance", without it NONE of them would be on the road

[will e]

on my holley unit it had a wire that was used to detect the engine was cranking so it would power the fuel pump. You certainly should have power 12volts of it, going to the fuel pump while cranking. I cannot see how it could work otherwise since without the pump and pressure the injectors won't squirt.

[Tad]

Pretty much the same thought as will e above. My Holley Projection setup sends power to the pump the second you turn the key.

[FSJ Guy]

AFAIK, ther are some pin-out differences between the different ECMs and the EBL unit. I'd verify that your wiring is correct, fiesta. There is no good reason that flipping the polarity of the power to the fuel pump should cause it to work. That part is odd.

And as mentioned, check your crank trigger wire.

[mike gw]

Well had some more time to look at it.
The problem is not fuel, the fuel pump is not getting power because there is no spark. I powered up the fuel pump with a jumper wire, and still no start.
So now the question is why no spark.
I have already replaced the module twice, both times it fired right up afterwards, the last time was Saturday. Today I replaced the new coil I had got with a old known working one, and it started right up. I drove it home, shut it off, went back out 10 minutes later, no start, no spark.
So what gives, are these parts bad, or is it the act of changing them that changes something.. I have two brand new connectors on the coil, and all other connectors and wiring look good. I will go look at wiring again, but it is strange.
I have the coil mounted on the intake, and the module mounted on the arm for the air pump. I had it this way for the last four years trouble free, until I rebuilt the engine.

**I emailed Bob from EBL this morning, and to my suprise got a very quick and complete response to my questions.** I am impressed with the product and customer service.
Check out his web site www.dynamicefi.com it is worth a look.

[FSJ Guy]

Are you running computer controlled timing? If so, the ECM will NOT fire the coil if it thinks the fuel pump is not working. It checks to see if the fuel pump has power in order to self diagnose the fuel pump relay.

Also, you mentioned your ignition module. If you're running computer controlled timing, the GM module must be GROUNDED via one of the screw/bolt holes AND have a good heatsink on it.

Those are the only things that came up for me when I read your last post.

[mike gw]

I am running computer controlled timing.

I was worried about the module mounting location, but it has been fine for years. I do have a ground wire running to it, and it is bolted to a steel plate, that is bolted to the diverter valve bracket.

So I have been thinking about the ignition vs fuel problem, and I am more and more convinced that the ignition problem is causing the fuel pump not to power up because it is not getting spark.

That leaves me with why..
When I rebuilt the motor, I got an accel coil and module, they have both now been replaced, (with the old parts) along with an additional module from napa.
So far everytime I have replaced something, it fires right up, and runs fine, until I shut it off, then no spark again.
I am going to pull the wiring apart tonight, and double check everything.

[FSJ Guy]

Then it's back to basics. Does the fuel pump power on for about 5-10 seconds or so when you first turn on the system? Passing this test proves the fuel pump is wired correctly and is working via the ECM.

A trick I do to test the distributor pickup is to loosen the distributor, and turn it enough so that the starwheel should trigger the ignition. (Do this with the key on, engine not running)

When the ignition is triggered, you should hear the injector click when it fires. If the system passes this test, you know that the distributor, ignition module, coil and injectors are all working as they should.

If you STILL have a no start condition, I'd look at the crank trigger wire. Make sure you are CONSISTENTLY getting 12V when the ignition is in the CRANK position. Also verify that you have 12V to the ECM in both CRANK and RUN positions.

I know, it ran before, but double check it anyway.

I sure sounds like an intermittent open. Those are the worst to diagnose.

[Woodchomper]

mike.....Can you tell us more about your setup?

(Q1)Were you running a successful TBI setup before you switched to EBL.

(Q2)Did you install the EBL board in the ECM or did you buy an ECM with the EBL installed.

(Q3) What wire harness are you using (Painless, Howell, or GM)?

(Q4) What distributor are you running (motorcraft, MSD, GM)?

(Q5) What type coil are you using (TFI or GM)?

I'm running the EBL Classic in my Wagoneer. Bob has been an excellent source of information. Also, there is a ton of info on tuning and setting up an EBL TBI at http://www.thirdgen.org

FSJ Guy's advice has been spot on. If you can follow up on his suggestions you should be up and running in no time.

[mike gw]

Thanks for the tips guys...

Ethan - the fuel pump is powering up like it should. A few seconds when key is turned to on. I have a fuel pressure gauge mounted on the back of the TB, and I have pressure.
After I took off the acell coil, and put on the stock one, it seemed to run better than before. I had questioned that coil, because when I was timing it, I was getting somewhat erratic spark on #1. The thought I had today was the pickup sensor in the distributer. (I am using the distributer from my doner engine, which I didn't use with the old engine. (don't want to mess with the cam gears) I welded the mechanical advance, and the vac advance is hooked up inside the Dist. but no vac line going to it. I may try to take the sensor out of my old Dist. and swap it in, see what happens.... Thanks again for your ideas!!

Woodchomper - I bought the tbi system off ebay like four years ago. I have had it on my Wag. since, and it has worked flawlessly. It is a GM harness, GM coil, Jeep (motorcraft) dist., and a 747 ecm. With the GM module and computer controlled timing. The reason I went with the ebl, is My engine blew, so I rebuilt it, bored .040 over, with an rv cam. I did not want to deal with the chips, tuning my new engine.
I do love the ebl system so far. It does what I always though TBI should be able to do. And Bob has responded very quickly to my questions, and seems very good at this stuff. I had him send me the whole ecm/ebl all ready to go. (and he said I can send my old one back for 50 core)

So the bottom line is, as frustrating as tracing open circuits is, with a new engine I will take it over, strange internal engine noises, or leaks (mine has neither) knock on wood.

[FSJ Guy]

There was a guy on the board a week or so ago that had a bad pickup in the distributor, too. It might be worth a look.

[rmorit01]

I can only suggest checking and replacing any of the fuses that are in your relays.

I was tracking down wires only to find a blown and loose fuse connection.

However, that is at the check the basics level...but no voltage was going to the the fuel pump.

Bob

[Woodchomper]

Mike - I was re-reading your post and I just can't get past the fact that you do not have 12V to the fuel pump when cranking. I looked over some notes I had on my Wagoneer's wiring and here is what I found.

1. Fuel pump power 12V (orange wire - fused) is connected to the battery, ECM pins B1 and C16, fuel pump relay pin A, and one side of oil pressure switch.

2. The Oil pressure switch closes at 4 psi. This is what provides power to the fuel pump when the engine is running.

3. The fuel pump relay is used to provide power to the FUEL PUMP when starting the engine, and for the first 60 seconds when the ignition is turned to the "on" position. ECM pin A1 outputs 12V to drive the fuel pump relay during cranking and when the key is first switched on.

4. ALDL pin G (red wire) can be used to test the fuel pump. If you apply 12V power to ALDL Pin G the power will be routed through the normally closed contacts of the fuel pump relay.

5. ECM pin B2 is used by EBL to monitor the fuel pump voltage.

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Now back to your problem, you used the EBL WUD display to watch your fuel pump voltage (ECM B2) when you first turned the key to the "on" position. In this case you saw 12V and then it went away. That is normal. This tells me that the ECM fuel pump relay drive pin A1 is good, the fuel pump relay is working, and ECM pin B2 is good.

You also stated that there was no 12V fuel pump voltage present during cranking. No voltage during cranking tells me the ECM does not know the engine is being started. During starting, 12V is applied to ECM pin C9 (crank signal). This signal should be tied to the starter solenoid. You need to verify this signal. If this wire is open or if the ECM has a bad input pin at C9, the fuel pump will never get power during cranking.

As far as your coil and distributor concerns, I would wait to work on those problems until you get the fuel pump working. The only other thing I can think of is to verify your fuel pump relay is powered by battery power and not ignition key "on" power.

[mike gw]

Update!!!
I had a few minutes this evening, and swapped out the dist. pickup, from my old dist.

***When I got this system running a couple weeks ago, I figured I had a lot of tuning to do, would need to give it gas to start cold, and ran bad when cold. ran ok when warm, but didn't have the power I thought it should. Of course I have only put about 15 miles on it to date.***

So I get the pickup hooked up, I reach in an turn the key, just to see if it trys. It fired right up!!! no smoke, no smells, no giving it gas to keep it running, it just started and idled!!! I am starting to believe that is what my problem was... I am not getting too excited yet, but it is looking good.
It also would make perfect sense with my fuel pump problem, since the pickup signal triggers the injectors. (when cranking) If I understand the system correctly. I didn't have the laptop hooked up, and only ran it for a minute in the garage.
Anyway, I will update again once I can drive it... (its getting late tonight)

[FSJ Guy]

Great news!!!

You can buy a new sensor (Hall effect sensor, IIRC) from the parts store. You don't have to get a whole new distributor.

I may have to add this to my spare parts collection, too.