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Tried starting my motor after TBI swap today

doonjumper

doonjumper

1/2 ton status
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Visalia, California
Tried to start the motor this afternoon. No luck. Its timed right. Starts if gas is manually put in. Fuel is cycling through carb. Injectors shoot one very quick and small burst of fuel while cranking. I noticed that there is fuel on the top of one of the injectors. New Dist. so module should be good. Ill check to basics tomorrow. Im tired. Just have to go through everything again. I did notice that the painless orange idiot light doesnt come on when I turn the key on. Got the ECM and chip from eaglemark so I know its good. I disconnected the TPS in case I was getting a high reading making the ECM think it was flooded therefore shutting down injectors. Still no change. Probablly has something to do with fuel on top of one of the injectors. Its leaking obviously.

Any ideas of where I should start looking tomorrow? I may have the wrong fuel pump. I used the one that came with my TPI. Maybe pressure is too hi or something.
 
doonjumper said:
Tried to start the motor this afternoon. No luck. Its timed right. Starts if gas is manually put in. Fuel is cycling through carb. Injectors shoot one very quick and small burst of fuel while cranking.
Click to expand...
Is the crank wire hooked up to correct post on starter? Needs to get power when in crank!

Fuel on top of an injector is an issue but unless it's pouring down it should run, may be the O rings under injector or injector not in right position, they have a notch and it only goes one way.

TPI pump is fine, been done before, the regulator will handle it. As long as return line is clear to tank.

Check engine light needs power to it and the wire to ECM is ground. When hooked up right it tells a lot. Key on it will come on, blink off to on and stay on till engine starts.
 
I have test light at the injector. It has power when key is on and dims a bit when in crank mode. No pulse. Test light stays solid. That explains the 1 small burst at start up. If I bum start the motor the injectors shoot fuel everytime but thats it......nothing while constant cranking.

Fuel supply and return are strong. Not clogged

I notice that the painless harness has a plug labled fuel pump relay. I dont have a plug to connect to it. I only have +/- wires (summit universal harness) connected to the fuel pump. Maybe the ecm needs some kinda input from the fuel pump?

Thanks for the help by the way. Donation heading your way :bow:
 
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I notice that the painless harness has a plug labled fuel pump relay. I dont have a plug to connect to it. I only have +/- wires (summit universal harness) connected to the fuel pump. Maybe the ecm needs some kinda input from the fuel pump?
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Bingo! Pin B2 gets a signal from fuel pump relay when it is on. Look at the wiring diagrams here:
http://coloradok5.com/forums/showthread.php?t=302678

Also is the crank wire hooked up?

ECM also supplies the power to turn on fuel pump relay.

You got spark right? No spark means no DRP signal to ECM and no injector fire...
 
I spoke to soon. What I did was take a jumper wire from the fuel pump and connected it to the painless relay plug orange wire. Now I get fuel during start mode BUT the fuel pump stays on after I shut the vehicle off. So I need to wire in a relay. I took Marks schematic he supplied and drew in a relay. That's all I need to do right?

I spoke to soon. What I did was take a jumper wire from the fuel pump and connected it to the painless relay plug orange wire. Now I get fuel during start mode BUT the fuel pump stays on after I shut the vehicle off. So I need to wire in a relay. I took Marks schematic he supplied and drew in a relay. That's all I need to do right?
1) Cut fuel pump wire and attach one side to the 30 side of relay and other side goes to A on plug
2) Other side of fuel pump wire goes to the 86 then to D on plug
3) Ground goes to 85 on relay then to F on plug
4) That leaves 87 going to E on the plug?

Is that right?

*Edit* disregard above. Most of it is wrong. Ive been looking online and have come to that conclusion lol. One thing at a time. I will wire in the relay then figure out which wire goes to the Painless plug after that. One step at a time. One of these days Ill learn the read a schematic. Maybe my new years resolution lol

eaglemark.gif
 
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Is your harness wired for the relay that came in GM TBI? Like this? Just plug one in. Easy JY or auto part store part.
attachment.php


Your trying to wire in a Bosch relay.
85 or GM relay pin F to ground
86 or GM relay Pin D Trigger relay on from ECM Pin A1
87 or GM relay Pin E Power to pump
87a to ECM Pin B2 (tied in GM relay)
30 or GM relay Pin A Power in, this comes from battery and tied to give power to ECM, not power from ECM.
There is no Pin C in a Bosch relay, it is a test or prime wire for GM relay.

attachment.php


http://www.gearhead-efi.com/Fuel-Injection/showthread.php?180-Fuel-Pump-Relay-Wiring

fuelpump_relay_wiring.gif

GM_Fuel_Pump_relay.jpg
 
Wow so I was close to getting it right then. I just didnt account for 87a

It has a plug like the one in post #8 CADFE. It also came with the one you posted in post 9 that a person could re-wire to. Orange, red test, Green/white, black/white, tan. I dont have any of those plugs because I installed a Summit universal and all they supplied was 1 yellow wire marked Electric fuel pump. Thanks again for the help. Im shocked I almost got it.
 
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Some relay don't have 87a, it's just another power output. You could tie the signal to ECM from 87.
 
eagle mark said:
Some relay don't have 87a, it's just another power output. You could tie the signal to ECM from 87.
Click to expand...


:haha:Now thats some funny stuff right thar! I went out a couple hours ago and wired it all up. I got the pump to prime for 2 sec but no fuel during start mode. I used test light to determine that the B2 (tan/white) wire does not have power when key is in on position. It only powered through start mode. Yet when I ran it through the relay 87a it was the opposite, had power when key was on but no power under start mode.....so I had no hot feeding the pump after prime. I didnt understand how the wire could be powered during start mode only at the dash, yet had no power at start when plugged into 87a on relay. I by-passed the relay and hooked it up to the fuel pump wire and it started right up (got fuel). I changed the relay and that fixed the problem (relay's were identical). BAD FRICKIN RELAY! But you know what? I learned alot and thats worth it in my book! Thanks again. Relay works every time. Pump primes for 2 sec and shuts off though the relay, then pump turns back on during start and when engine builds OP that signal takes over.
 
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Glad that's over!

The Oil Pressure switch is redundant, it does not really take over, many aftermarket systems do not use an OP switch. I don't know why GM went through all that trouble but it was to keep engine running if relay failed.... but would never start again if turned off with bad relay...
 
eagle mark said:
but would never start again if turned off with bad relay...
Click to expand...

According to GM, the engine SHOULD start with a bad relay, it just takes longer. Oil pressure will build up, switch closes, pump runs.

I've done this before, you SHOULD be able to unplug one or the other from the system and start the rig, OR disconnect one or the other while the truck is running.

Some setups seem to have a bit harder time starting without the relay.
 
I went out and put bad relay back in and no start. It cranked but no fuel to objectors. Put working relay back in and it fired up.
 
If your wiring follows this schematic http://coloradok5.com/forums/attachment.php?attachmentid=138958&d=1356405485 as long as the engine develops ~4PSI oil pressure during cranking, the switch works, and the wiring is good, it has to start. GM says "prolonged starting" will be the result of a failed fuel pump relay. I'd directly quote the '91 R/V manual if I had it in front of me.

As you can see, the same wire that goes to the oil pressure switch is the same one that switches the relay...if the relay works, the oil pressure switch is getting power, assuming the wire is good.
 
I beleive you, howeve. I've switched relays multiple times and it only starts with one of them. Maybe its wired different. Relay clicks open and closed when its suppose to and rig starts so Im stoked.....it is odd though
 
Well if you have the switch in place and it's easy enough to get to, you might try jumpering the two terminals in the connector, it should run the pump regardless if the engine is turning or not.

I tried this on my truck (TPI) and my Dad's TBI, and I do recall that one of them took some "coaxing" to get to work the way it should...like I had to connect it, disconnect it, then reconnect and it finally started. Otherwise, like you say, it wouldn't start with the relay disconnected. I'm attributing it to bad connections.

It's nice to have it running though! :)
 
I forgot that I had an autoXray EZLINK Version 1.44.... Yeah its old lol. Its older unit here is the capture

Prom ID- 6091
Idle Air- 35 steps
Coolant Temp-185
Map- 1.15
RPM-825
TPS-0.54
Integrator- 126
02 sensor-884mV
Batt V- 12.6
Knock-13
Block learn- 128
02 Cross- 163
Rich Lean Flag- captured Lean but showed more rich than lean prior to capture
Loop-closed

Anything jump off the screen. Had a low MAF/MAP error code 34. I am running the most aggressive Computer cam according to COMP CAMS.
 
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