Will not start

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grimprime221

Member
Re: Will not start

Don W. said:
Yes you can AFAIK. Just swap the chip into the new one. I thought I saw some here for sale recently.

Power to the injs can mean different things. One wire is hot all the time (key on) the other two provide ground to actually fire the injs. So unless you have the test gizmo you probably can't tell. So 12v on the one wire is only half the story. Assuming that's what you're talking about.
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Wanted to avoid swapping chips until sure ecm is the problem. New to the computer end of the trucks so hesitant to mess with anything other than wire swapping. I tried the injector test light not sure I did it right but did not light on turning engine over.
 
SevenT6Vet

SevenT6Vet

New member
Re: Will not start

I'm subscribing to this also. My Typhoon has exact same issue with these subtle differences:
-my truck is stock
-my truck takes 20 cranks to start if it has been longer than a week. Less than a week it takes 3-5 starts. On a same day restart, 1-2 cranks.
-if cold restarting, ether will make it start immediately
-vehicle idles and drives fine
-fuel pressure is ok when primed (key on, engine off)
-the following parts are new: ignition coil, ignition module, cap, plugs, wires, coolant sensor to gauge, vacuum lines
-original to the truck: fuel pump
-coolant sensor to ECM appears to be fine while driving according to data log (i have not checked temp reading prior to starting, though).

Sounds like I need to check: TPS voltage and oil pressure sensor/relay (oil pressure gauge reads fine)
 
Don W.

Don W.

Stab it and steer it
Re: Will not start

The oil pressure sw is a backup to the relay circuit. You say "fuel pressure is ok when primed (key on, engine off)" Turn the key on and don't try to start. Fuel pump should run for 2 seconds. Does it? If so then relay circuit is good. If not swap the two relays on the upper left corner of the firewall drivers side.

Does fuel pressure stay up while cranking?

There is a fuel pump test plug by the dist. Just hangs there. It's the female end of a blade connecter. Connect 12v to that and the pump should run with key off. Jump that to 12v, (The terminal block right there is hot all the time.) leave it jumped and see if your cranking issue goes away.

Fuel pump circuit operates in this sequence: Key on fuel pump runs for 2 secs. (If you go direct from key off to start you won't even notice this.) Then the ECM looks for a pulse from the dist. (Obviously the motor has to be cranking for this to happen.) If there it keeps the fuel pump running. (Both of these use the aforementioned relay.) If none of this happens then the oil pressure sw will run the pump directly, no relay, once there is oil pressure.

All this assumes the fuel pump is fully operational.

HTH
 
SevenT6Vet

SevenT6Vet

New member
Re: Will not start

Don W. said:
The oil pressure sw is a backup to the relay circuit. You say "fuel pressure is ok when primed (key on, engine off)" Turn the key on and don't try to start. Fuel pump should run for 2 seconds. Does it? If so then relay circuit is good. If not swap the two relays on the upper left corner of the firewall drivers side.

Does fuel pressure stay up while cranking?

There is a fuel pump test plug by the dist. Just hangs there. It's the female end of a blade connecter. Connect 12v to that and the pump should run with key off. Jump that to 12v, (The terminal block right there is hot all the time.) leave it jumped and see if your cranking issue goes away.

Fuel pump circuit operates in this sequence: Key on fuel pump runs for 2 secs. (If you go direct from key off to start you won't even notice this.) Then the ECM looks for a pulse from the dist. (Obviously the motor has to be cranking for this to happen.) If there it keeps the fuel pump running. (Both of these use the aforementioned relay.) If none of this happens then the oil pressure sw will run the pump directly, no relay, once there is oil pressure.

All this assumes the fuel pump is fully operational.

HTH
Click to expand...

Yes, when I turn the key the fuel pump primes for 2 seconds, then shuts off. Listening for this helps me start the truck quicker. If I turn the key on, let it prime, then crank (no start)...my next step is to turn key all the way off, back on, let prime, then crank INSTEAD OF turning key back to on, then immediately cranking again. The full off-on (hold for 2 seconds) then crank will get it started quicker than on-crank-on-crank, etc. [hope that all made sense]

I have not tried jumping 12V to female pin.

Approx a year ago, I borrowed a fuel pressure gauge and the pump brought pressure up to 43 psi and would hold it there. Turning key off it would still hold that pressure for a while. When cranking, it seemed to fluctuate some, but still in that range. The situation has not gotten any worse, nor better since then. I've just been living with it since I only drive it about once a month or so.
 
Don W.

Don W.

Stab it and steer it
Re: Will not start

SevenT6Vet said:
Yes, when I turn the key the fuel pump primes for 2 seconds, then shuts off. Listening for this helps me start the truck quicker. If I turn the key on, let it prime, then crank (no start)...my next step is to turn key all the way off, back on, let prime, then crank INSTEAD OF turning key back to on, then immediately cranking again. The full off-on (hold for 2 seconds) then crank will get it started quicker than on-crank-on-crank, etc. [hope that all made sense]

I have not tried jumping 12V to female pin.

Approx a year ago, I borrowed a fuel pressure gauge and the pump brought pressure up to 43 psi and would hold it there. Turning key off it would still hold that pressure for a while. When cranking, it seemed to fluctuate some, but still in that range. The situation has not gotten any worse, nor better since then. I've just been living with it since I only drive it about once a month or so.
Click to expand...

Hard to say from all that. I'd try jumping the test term first. Very simple and quick. If it still takes some cranking to start then it's probably not the fuel pump. Only way to know for sure is to have a fuel pressure ga on it while checking.

Assuming the fuel pressure is good and it still takes some time to start then you've eliminated fuel supply as the issue. Could be a handful of things after that.:(
 
G

grimprime221

Member
Re: Will not start

I didn't think of oil sensor tried disconnecting that and still no start but think battery is weak from not being run. That and its 20 degrees in the garage.
 
Don W.

Don W.

Stab it and steer it
Re: Will not start

grimprime221 said:
I didn't think of oil sensor tried disconnecting that and still no start but think battery is weak from not being run. That and its 20 degrees in the garage.
Click to expand...

20 degres and a low battery ain't gonna help. Disconnecting the oil pressure sender is kinda going the wrong direction. It's the source of last resort for juice for the fuel pump. Did you ever print the "no start" PDFs I posted and follow them?
 
G

grimprime221

Member
Re: Will not start

The tach did flutter more with the sensor disconnected. I followed the sequences for no start only thing that I seem to find is the noid light test I do not get it to light up.
 
Tony Dipatri

Tony Dipatri

New member
Re: Will not start

SevenT6Vet said:
Yes, when I turn the key the fuel pump primes for 2 seconds, then shuts off. Listening for this helps me start the truck quicker. If I turn the key on, let it prime, then crank (no start)...my next step is to turn key all the way off, back on, let prime, then crank INSTEAD OF turning key back to on, then immediately cranking again. The full off-on (hold for 2 seconds) then crank will get it started quicker than on-crank-on-crank, etc. [hope that all made sense]

I have not tried jumping 12V to female pin.

Approx a year ago, I borrowed a fuel pressure gauge and the pump brought pressure up to 43 psi and would hold it there. Turning key off it would still hold that pressure for a while. When cranking, it seemed to fluctuate some, but still in that range. The situation has not gotten any worse, nor better since then. I've just been living with it since I only drive it about once a month or so.
Click to expand...

I am developing the same issue
 
G

grimprime221

Member
Re: Will not start

DaveP said:
. Check the TPS voltage again:

Put your VOM on 20V DC scale.
Put the red lead on the blue wire of TPS.
Put the black lead on a good engine ground.
Turn on key. Voltage should be ~0.50 VDC. ( That's a "half-volt" 0.50 V)
Move arm to full throttle.
Voltage should be greater than 4.0 VDC.

If you don't see the above results (0.5V closed-throttle and over 4.0V at full throttle) Concentrate your efforts on getting TPS straightened out.
Click to expand...

Finally got time to test the TPS (hopefully correctly) as described. With key on it was showing between 1 and 2 and full throttle was just below 4.

Took a few tried since hasn't been run in a while but as has been the cases with starting fluid started and ran perfect once started.

Thanks to everyone who has been offering their help. Just can't find a better group of people with better trucks (even when they don't work) out there.
 
G

grimprime221

Member
Re: Will not start

Thinking I am going to break and replace the pump as that seems to be the most likely culprit at this point. Walbro 255 from what I have been reading is a common and good replacement. Wanted to make sure or if I have other areas in the system left to check before dropping the tank. Regulator maybe?

Had to move the truck today so got it started and tried driving it but sputtered and died any time over 15 mph or if I got on gas to go up hill. Thinking this confirms the pump is dying and has been the problem.
 
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G

grimprime221

Member
Re: Will not start

replaced the pump.

What is the purpose of the pulsator? Been reading to just get rid of it.

Also there was an o ring on one fuel line attaching to the sending unit. should there be one on both? anyone have a part # or size?
 
G

grimprime221

Member
Re: Will not start

Got the new Walbro pump in took out pulsator when I did. Whet to start and same crank with no go. Again fired right up and ran fine after a shot of either. I'm at a loss where to go next. Sensors?
 
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