fuel to throttle body but not to cylinders - JeepForum.com

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post #1 of 43 Old 10-05-2009, 02:51 PM Thread Starter
themole112186
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fuel to throttle body but not to cylinders

my 1990 wrangler died and had no spark and no fuel coming to the engine. after replacing the ecu i have spark and the fuel gets to the throttle body.. the thing i dont understad is how the fuel wont make it into the intake manifold even after i put in a new injector.????.

if i pour fuel into the intake the engine will start up but only till whatever i poured in gets burned up...

any ideas anyone????

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post #2 of 43 Old 10-05-2009, 02:55 PM
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You have gas at the bottom of the TBI after trying to crank it correct. You can see this when you pull the TBI cover off and open the throttle with your hand correct.

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post #3 of 43 Old 10-05-2009, 02:57 PM
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Go ahead and fill out your profile. I know its a 2.5 since you said Throttle body cause the 90' had either 4.2 Carb or 2.5 TBI, but alot of people on here wont answer if you dont fill out your profile.

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post #4 of 43 Old 10-05-2009, 02:57 PM Thread Starter
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yes.......

its like the fuel gets to the tbi but doesnt go through..
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post #5 of 43 Old 10-05-2009, 03:02 PM
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only way it wouldnt go through is if it was blocked. Are you holding the throttle wide open when you try to crank it.

Just to verify, you have checked your spark plug wires to make sure there in the correct spot. Ask me how I know.

If there is fuel in the TBI then the injector is working. And that is the beginning of the intake manifold.

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post #6 of 43 Old 10-05-2009, 03:05 PM Thread Starter
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ive tried it with no throttle. half throttle. and full throttle .

it starts up runs fine until the fuel i poured in is gone
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post #7 of 43 Old 10-05-2009, 03:09 PM
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Can you hear the fuel pump kick on when you turn the key, not to the crank position, to the on position?

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post #8 of 43 Old 10-05-2009, 03:10 PM Thread Starter
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yes i hear that....... and ive disconnected the inlet line and seen the fuel squirt out.
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post #9 of 43 Old 10-05-2009, 08:19 PM
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Quote:
Originally Posted by themole112186 View Post
my 1990 wrangler died and had no spark and no fuel coming to the engine. after replacing the ecu i have spark and the fuel gets to the throttle body.. the thing i dont understad is how the fuel wont make it into the intake manifold even after i put in a new injector.????.

if i pour fuel into the intake the engine will start up but only till whatever i poured in gets burned up...

any ideas anyone????

Check your fuel line pressure at the fuel rail. If it is too low you get no fuel through the TB.

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post #10 of 43 Old 10-05-2009, 08:40 PM
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I will keep any eye on this, I have a 90' with the 2.5 sittng in my drive way for parthing out. If you need something let me know.

Also I have the 90 Chrysler Student reference Book for this injection system.

It says that the fuel psi should be 14-15. To check the fuel pump relay, speed sensor and that if the WOT switch is grounded fuel delivery from the injector will not occur. (ie holding it at WOT while cranking will cause it to not start) Also check for bad injector.
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post #11 of 43 Old 10-06-2009, 06:30 AM
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You can get fuel to the TBI, but if it is not going into the bottom of the TBI then either the injector or fuel pressure regulator is bad, maybe?

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And you keep the terrorists in check before you get your *** blowed off.
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post #12 of 43 Old 10-06-2009, 08:27 AM
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You can get fuel to the TBI, but if it is not going into the bottom of the TBI then either the injector or fuel pressure regulator is bad, maybe?
I forgot to mention the FPR!

That could also be the culprit. I would take the chance and replace the fuel pressure regulator but they do cost ~ $60 IIRC. Go the cheap way and get one from a bone yard.

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post #13 of 43 Old 10-06-2009, 05:26 PM Thread Starter
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Originally Posted by Why J? View Post
I will keep any eye on this, I have a 90' with the 2.5 sittng in my drive way for parthing out. If you need something let me know.

Also I have the 90 Chrysler Student reference Book for this injection system.

It says that the fuel psi should be 14-15. To check the fuel pump relay, speed sensor and that if the WOT switch is grounded fuel delivery from the injector will not occur. (ie holding it at WOT while cranking will cause it to not start) Also check for bad injector.

the pressure is fine im sure of that.

you wouldnt happen to know which of the 2 relays is the fuel pump relay??? (there are 2 right next to the battery).

where is the speed sensor?

can i tell if the WOT switch is bad just by looking at it or testing it in some way???

the injector is brand spankin new,,,, cost me a pretty penny. which is why im really frustrated it didnt do the trick..
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post #14 of 43 Old 10-06-2009, 05:28 PM Thread Starter
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Originally Posted by RebuildRookie View Post
You can get fuel to the TBI, but if it is not going into the bottom of the TBI then either the injector or fuel pressure regulator is bad, maybe?
the FPR is on the outlet/overflow fuel line right? how would that stop fuel from going through the injecter because the injecter is before the FPR in the fuel flow?????........
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post #15 of 43 Old 10-07-2009, 07:13 AM
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no the FPR is before the injector. look at the TBI close and you will see that the inlet is lower than the outlet (right above the inlet there is a allen head bolt that is screwed flush with the TBI block and it is even with the outlet). the fuel goes in then across and up the FPR then to the injector (it has to regulate it down to 14 or 15 psi before it goes to injector) then to the outlet.

The fuel pump relay will have 2 orange wires out of the 4 total wires going into the bottom. The ASD has 2 pink wires out of the 4 going into the bottom.

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You spray the ants before they get in your house.
You plant the crops before you starve.
And you keep the terrorists in check before you get your *** blowed off.
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