Greetings everyone,

I just adapted my 89 grand wagoneer to TBI. I am having an issue with the fuel pump. The fuel pump is not getting any power for some reason or another. The power in wire for the relay is active. But the tan and white wire (Power out) that leads to the fuel pump is not getting power for some reason or another. I have tested the wiring leading from the relay to the computer and all the connections and wiring are intact and after testing with a multimeter they are true conections. I purchased a new fuel pump relay and replaced it with another new one but still the same problem. I have put ether in the Throttle body and cranked it and it fires up no trouble at all. For some reason it is not getting fuel. I tested the pump and the pump works. What am I missing? IS there something else that I might have missed? I did install a painless wiring harness so maybe the pinouts were incorrect or something? I am using computer 1227747. I have heard that if the oil pressure switch is not functioning correctly that the TBI injection wont fire. ( I had to extencd some of my wiring and I had to use a quickie soldering iron so maybe I need to go back over some of the solder jobs and see if they are tried and true.) what do you all think? could one of the other sensors or something else be affecting the fuel pump power wire? What am I missing?

Maybe there is something I didnt do in the computer (Program) that needs to be done. What do you all think??

 

Wagon'

The fuel pump relay coil should have 12 Vdc (pink) and ECM control wire which ECM pulls down. The most common mistake is not to have 12VDC at the relay coil during cranking. This happens if relay wire is wired to a circuit that gets cut out during cranking. Get your DVM and check and see if the circuit that supplies power to the relay gets 12VDC during cranking.

//RF

 

ok everyone I just tested my circuits. The fuel pump wire is getting power but only for about he first three seconds. After that it cuts out and doesnt get anymore power. This I guess lets me know that the relay is activating but it isnt doing anything further from there. Do you all have any idea what could be causing this? Someone mentioned that the fuel pump actually is only activated through the relay for a short period then it switches to the oil pressure switch and is grounded through there or something to that effect. is that what it could be?? maybe not?

 

Wagoneer

If fuel pump relay gets power during ECM power up for about 2 seconds - when ignition key goes from off into run position. Your FP wiring is OK.

What happens during engine cranking is that ECM is looking for DRP signal from dizzy indicating that engine is cranking. If ECM sees these pulses it will enable FP relay. Otherwise oil pressure switch will enable FP after extensive cranking - oil pressure switch will close at 6 PSI. Oil pressure switch is only used as a backup device to fuel pup relay. Verify that ECM enables FP relay with a DVM by putting test leads into relay socket (temporarily remove relay, or backprobe) across coil contacts - check you harness documentation, usually it is green-white and tan color wires used for FP coil.

Q1 - do you hear fuel pump when you transition ignition key from off into run position?

Q2 - do you see SES light blink on - off - on during the same time?


//RF

 

ok here is the situation. I just re-tested it and I have two computers. I have the EBL classic that I ordered months ago and Just got around to, and I have a junkyard 1227747 computer that I just purchased a few days ago. I think that the EBl board may have been damaged during shipping but not sure. Anyway when I connect the EBL computer the check engine light stays constant and doesnt do anything. When I switch it from run to start it just stays constantly lit. THe computer I got from the Junkyard actually flashes on then off then on when I turn it to the run position. The junkyard computer actually is the one that I have been able to get to fire up the pump for the initial two seconds. THE EBL computer does nothing except for keep a constant check engine light glowing, even if I turn it to the run position the light just stays on constant.. It doesnt even give power for the initial two seconds.


When I hook up the 1227747 stock computer I can hear the fuel pump relay click (I dont hear the fuel pump but its under the rig so maybe it is but I just dont hear)


The EBL computer simply does nothing. No fuel pump no sound no clicks no nothing.

Please help!!! this newbie is really lost on this!

 

Wagon'

Lets take this problem into separate parts.
1)
Connect EBL ECM to your lappy (use heads-up display) and verify that a baseline BIN file supplied with your EBL package is loaded into FLASH memory and that location is selected as active. If there no bin ECM will never boot up (solid SES) - it's should be a very easy fix. Also, read documentation supplied on CD
2)
With 7747 JY special ECM should be sufficient enough to get things fired up. Since you are getting on - off - on SES blink action and two second FP prime you are in relatively good shape. In your case you have EFI retrofit into a carbed vehicle - make sure that IGN line to ECM gets juice during cranking. This is a very common problem. Verify that your IGN line to ECM is hot during cranking. If you are using radio fuse for a IGN line to ECM tap it maybe shutoff while starter is cranking - injectors and fuel pump will never get turned on! Get a DVM and verify that it is hot during cranking - let me know in the morning. (I have been there myself!)

//RF

 

RFMaster I wanted to Personally thank you for all of your responses. You definitely have me going in the right direction and I know that I am going to solve the riddle soon enough. (Man I am such a newbie at this). Anyway I pulled my EBL computer and I am going to fiddle with it now and activate it properly. I need to change some things here and there in it anyway so I might as well get it done. I also tested the fuse/wires that I had my ECM connected to. It is a wire that gets 12 volts during the on position but when turned to run the voltage drops to about 10 or 11 volts. I think that this may be the culprit. I am going to unhook the ecm wire and connect it to a wire that gets 12 volts at all times (in the run and the start position) This I feel will probably kill out this problem and it should start after this. Thank you again for all of your help. I wont be able to try this out until tommorow as I could not beat the sunset and my rig is in a remote location. I figured it would be best to just do it in the morning. I will post the results after trying it and of course I am going to activate my ebl computer properly and get both computers up and running properly (Never hurts to have a spare and I am getting a spare of every sensor as well for a carrying case to keep for emergencies.)

 

Glad to be of help.

In my case, I used a separate 30 Amp relay ( BOSCH type, about $4 and another $3 for a socket) getting juice directly from main 12 DC bus, via in-line fuse, at the battery. Coil on that relay is activated from fuse box that stays hot during run and crank. Use 12 AWG wire to minimize voltage drops - to feed injectors and ECM. For real nice results I used Painless Wiring switched fuse panel #70107. OEM fuse panels might be insufficient due many junctions and results in voltage drops. Even though, 10 to 11 volts should be sufficient for ECM to fire injectors. Verify that injectors are getting constant +12 volts on red wire and blue and or green wire are pulled down to ground, test light blinks during cranking. Verify all your grounds.

Take a look at my video (see the temporary wires, relay and ses action)

http://www.youtube.com/watch?v=sfxuOOliRdg


Did you use aftermarket or OEM harness???

//RF

 

Hello again,


Thanks for your responses, I am using a harness from painless wiring. Maybe the harness could be the problem perhaps??? ANyway I hooked it up to a 12 volt constant power supply and had the same results. Because of the fact that I never hear the pump initialize could it be the fuel pump that is maybe bad ?? Or maybe one of the sensors? The ignition module or maybe the ESC module? When I initially hooked up the ignition module I had the negatve and positive wires from the reluctor mixed up so maybe I blew it out or something. What do you think? any other directions that you may be able to think of?

 

Wagoneer

Depending on your installation verifying FP operation can be either straight forward or some what messy.
1) External inline fuel pump is very easy to check. Make sure that wiring harness (gray wire) from FP relay is connected to a positive terminal of the FP. Negative terminal should be connected to a good electrical ground, or preferably, a complementary return wire should be run to a system ground. Connect DVM or a test light accros FP terminal - cycle ign key from off into run position.
2) If no +12 at FP, remove FP relay from socket. Get a test light (or DVM) connect across relay coil contacts. You should see +12 Volts for about 2 seconds during ign off to run position cycle between black/white and green/white wires of the FP socket - per (60101 Painless) docs. Black/white wire should be connected to ground and green-white goes to ECM Pin A1. Open ground is a show stopper. All of the above are easy checks!
3) In tank FP - same as above, just make sure that gray wire gets +12 VDC to the pump terminals.
4) Check fuse supplying FP (orange) relay is always hot (battery, via fuse)

//RF

 

ok The puzzle is slowly but surely coming together. I was able to get the fuel pump to finally cut on for the initial three seconds. The ground wire must have been shorted or something I actually ran a new ground wire and voila. Now when I turn the key the relay gets power for the initial three seconds and the pump fires up!! Just hearing that and at least making headway was great. Thanks RF. I still cannot get it to power on for more than that three seconds. After the first three seconds the power shuts off. I set the timing in the distributor at TDC so maybe this has something to do with it. Who knows what the timing on the junkyard special is set at. I still cannot get my EBL board to work. I have tried everything and it will not activate. I am only able to get anything to initialize with my junkyard 1227747 computer. (I went into the whats up display etc etc and still cannot do anything with the ebl board. I guess I have no alternative but to send it back to the manufacturer. Anyway now that I have gotten the pump to suck up fuel for the initial three seconds its time to tackle the second problem. Why it wont get constant power. If the injectors dont get power or the distributor does not get a signal then the fuel pump will not stay activated correct? (I think I will tackle that in the morning and see what I am getting and if I can get this thing started. Thanks for your help again RF and what are your suggestions at this point? (In the morning I am going to test if the relay is switching from to the power lead, and secondly I will test if the injector wires are getting 12v power. (Gotta have someone with me to test that so that they can crank while I test)

 

On my '83 CFI Z28 there's a power feed to the OPS from the battery.The fusible link was cruched in the process of working on her - but didn't notice.I got her back together and no fuel.It was after checking the wiring diagram i knew where the wire went to.Replaced it and then had fuel and she fired up.Maybe this could be an area to look.

 

It is normal during ign key off to run position for the FP to run for about 2 seconds and then shutoff. For the ECM to fire injectors and turn on FP during cranking it must receive DRP pulses from dizzy. Which leads me to my next question what kind of dizzy do you have??? Since you have 360 in your rig you'll have to make sure that OEM dizzy is capable of providing DRP pulses back to ECM. This can be done by converting stock dizzy to a GM style 8 pin ignition module. I'm no expert in converting dizzy's but if you google it will pop up. Look at mega squirt page and Binder Bulletin's pages for conversion info. Without DRP pulse ECM will never enable FP and fire injectors - simple as that.

Happy New Year

//RF

 

this shouldnt be an issue, I actually converted the stock distributor to a GM hei distributor before I decided to do the TBI swap. (It ran fine then) It initially started as a GM Big cap HEI with a 4 pin module. I did the module swap as stated on the net and converted it to the 7 pin module (By doing such the module still fits in the dist) I am thinking that the new module that I purchased might actually be bad. That might be the problem area. Otherwise everything else is firing up as expected and all ground are tight and ready to go.



Happy New years, to all thirdgen members and thanks to all of you for your help. (I will get it to start someday lol)

 

Happy New Year as well - a year of the RAT!

Do you get a spark when you crank?? If not, also make sure that reluctor coil connector is plugged in correctly into 7 pin module.

7 Pin ignition module was used in large hat HEI with CCC or EFI - a drop in replacement for 4 pin vacuum advance controlled HEI for SBC. My guess - you'll have to check - the same is true for your application. When I did my conversion I simply bought (pulled) a used 7 PIN dizzy from JY (about $20) and after some cleaning and R&R it works fine in my rig. It is also possible to retrofit 4 pin HEI to 7 pin, but IMHO it is more hustle than its worth.
When cruising JY look for early 80's chevy equipped cars and trucks. Early third gens and trucks that used CCC can also be used. Look for missing vacuum advance and 4 wire pig tail with weather pack connector. Avoid V6 as you'll have to replace reluctor ring to V8 version - not worth hustle and money.

//RF

 

okay, I made some headway. I am getting power to the fuel pump and its actually pumping fuel (For the initial three seconds) I tested the injectors and they are getting power (12v). I tested for spark and I am not getting spark. That leaves me to believe that the culprit is the ignition module or the ignition coil. Let me know what you all think. What else could affect spark???

 

Little by little will get to the bottom of this stack

1) Make sure that you have +12VDC on the white (brown looking ) clip on connector with a pink or red 12AWG wire - thats your ignition power which is connected to BAT terminal of your dizzy. Just turn ignition key to run, and start and verify that you're getting 12 VDc with a DVM.

2) Verify coil ground strap is connected to the coil frame.

3) Check in cap ignition coil windings - open winding will cause no spark.

4) Verify that 3 wire jumper cable from ignition module to ignition coil contacts is plugged into cap socket.

5) Check carbon center feed through contact makes a good contact to rotor feed and output terminal of the coil (HV terminal).

6) Measure resistance of reluctor coil - it should be between 600 and 1500 Ohms.

7) Test ignition module at auto parts store.

8) The usual - worn tower contacts and rotor, carbon streaks inside dizzy hat.


//RF

 

Additionally, I replaced the coil just to see if that is possibly what it could be and it wasnt. All fingers are pointing to the module but it doesnt have symptoms of a bad module. Or are the symptoms actually module symptoms. I also got a spark tester and it is getting spark every once in a while but the spark is weak, and it is intermittent. (There is something going on here, I dont care if I have to replace every ignition component I have I will get it to start!!!) Another thought, could it be the ESC module? That is the only thing that I got used and not new.

 

Ok Wagoneer

Looks like you covered the check list fine - Item 3 can be disposed of since you have tried new ignition coil (in cap ignition coil). Replacing ESC module - square looking thing with four offset mounting holes is completely unnecessary. ESC module is an analog amplifier that receives signal from knock sensor (KS). If signal from KS is at a right frequency and above certain threshold ESC will produce digital signal for ECM input. ECM monitors this input and if it present for a certain period it will retard commanded timing. During start ECM has no control over timing since engine RPM's are below 400 RPM. During start, ICM module inside dizzy runs fixed timing. But once engine RPMs exceed over 400 RPM ECM takes over. Get a new module - AC-Delco D1952 or equivalent.

//RF

 

Ok I have a new coil, and new module. I am now getting spark. If I spray fuel into the injectors it will start up for a few secs but not for long. I tested the fuel injector wires and I am getting constant 12v at the red wire (In start and run). The blue wire I don't get anything. The green wire I get 12v (In start and run) and the white wire nothing no flashes on the blue or the white wire. (I guess the computer is not activating the injectors. What causes this??? FUel injectors are not spraying any fuel (Dang I will get this thing to start one day lol)

 

In order for ECM to fire injectors it must receive DRP pulses from dizzy. For ECM to fire injector it must be able to pull +12 v going through injector to ground. ECM grounds must be connected to a good DC ground.

Disconnect both injector clip on connectors. Check Injector coil resistance with a DVM - good injectors should be right around 16 Ohms. Anything less is a suspect. If it reads open (the one that you pulled of the white wire is a possibility) it should be replaced.

Check four wire connector between ECM and dizzy.

//RF

 

injector coil resistance? so I connect an ohmeter to the two prongs on the injector and get the reading? or do I connect one connector to one prong on the injector and the other to the ground wire that connects to the injector?

Injector coil is what is losing me here. (I am going to get this thing started I just have to keep trying.) I wish I had just purchased a new throttle body instead of getting one from the salvage yard. (That is probably the trouble spot) everything else is new.

 

It is across injector terminals - see picture below. And, please disregard my previous post, I was thinking about TPI injectors. TBI uses low impedance injectors - coil resistance should be about 1.2 Ohms

//RF

 

You really have been a huge help in this. I am hoping that this will be the problem and it will get me on the road. If not then back to the drawing board. I really appreciate all your help. At least now it is giving signs of life. When I first started even the fuel pump wasn't working. I will try the injectors in the morning and see what the test results yield. Thanks again

 

well I went out and tested them and it seems the injectors are bad. They tested lower than 1.2. One of them tested around 1.0 and the other was almost not even on the scale. At least I have one more piece to the puzzle figured out. Will go and get myself some new injectors and a TBI rebuild kit (Rings, Seals, gaskets etc)

 

I just got back from JY - hunting for parts on another project. Injectors are easy to replace - the one around 1.0 OHms might be OK (due to DVM leads, calibration, etc) The second one probably has open windings. All you need T-20 TORX and flat blade screw driver to R&R.

//RF

 

Dangit, Retested them again with a multimeter with a lower scale. Anyway the injectors tested in right around 1.4 ohms. So I guess the injectors are not the trouble. Checked out the wiring everything looks good. I guess I should test if the 4 wire connector is getting continuity in all wires. (I dont think that is it) is it possible that the injectors could be clogged or the pressure regulator is clogged or malfunctioning. I am stumped maybe replacing the injectors anyway wont be a bad idea. What do you think?

 

You have to make sure that ECM is pulsing the control line down. If you look at TB injector one contact is always hot (12 volts fused in run and start) and the the other one gets pulled down to ground - activating coil in injector. Disconnect connectors from injectors. Measure which pins are hot (12 Volts). - I think Painless uses Blue and Red for constant +12, while white & Light green are pulsed by ECM Pins D14 D16. It is worth a check to see if those pins are fully seated. I do not believe that it is a case.

Make sure that you are getting 12 volts to ECM and injectors during cranking.

//RF

 

ok Rf,


I can finally get back to getting this rig to start. I was down with the flu for a few days and a cold front came through so let me get into some ideas here.

1. Checking if the ECM is getting 12v in run and start is easy and if it isnt fixing it is easy too. (No problem here)

2. If I check the injectors and they are not getting 12v in run or start, I thought the power to the injectors was controlled through the ecm so it probably is going to be a headache to fix correct?

3. I may have cut or frayed a wire in the harness when I was pulling it through the firewall and under the dash. I will pull it back out and re-check and see how it all looks. I checked the connectors at pin 14 and 16 and everything was seated.

I still cannot get these injectors to fire. So if I go through all of these things and they check out ok then what else could it be? Lastly, could the ecm possibly be bad????

 

Well I hope that you feel a bit better

Item 1 - that goes without saying. BTW 7747 ECM gets constant battery voltage on pin B1 (orange wire) and pin C16 (orange wire). ECM ground is PIN D1 (Black-white). It also uses ignition run/start supply ECM fuse Pin A6 (pink-black wire) - your colors might be different.
Item 2 - Injector supply voltage runs of a separate fused circuit - just make sure that when ign key in run (engine stopped) you are getting + 12 V on one of the injector connector pins. ECM pulls the other wire to ground thus closing circuit and firing injector. A common mistake is to connect this circuit to fuse that is disabled during cranking. Just put a DVM on it and verify that you are getting +12 in run and when cranking.
Item 3 - That goes without saying - check your harness. Also check grounds. Also do you have SES connected? Does it do on-off-on when transitioning from stop into run position??

//RF

 

1. ECM getting 12 volts during cranking

2. Wiring looks ok all grounds connected

3. Injectors getting 12v during cranking.

4. SES light does the on-off-on when cranking and when turned to the on position. (Just like in your video)


I am stumped. I have no idea what could be causing this. I think that I am intentionally being given the most difficult to get to run TBI system (as per murphys law) just so that I can know it inside and out better than GM lol. And so that I can stop being a cheapskate and get all new parts to replace the few JY parts that I have left.


Idea: maybe the ecm is bad or my timing is not right? Its set right at TDC (I thought the computer would adjust this?) or possibly a bad fuel regulator? (I got a used Throttle body the injectors test good under an ohmeter but alas I still cannot get it to fire up.)