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View Full Version : Dont hate me cause it wont start.....


dick.breakey
August 30th, 2010, 14:30
89 4.0 aw4/231 155k



i cant find anything different than what ive already tried. my rig has stopped starting on its own. take spray in the intake to do it. i replaced the fuel pump, now have a around 40psi while running, and no its back to not starting. if i spray stuff into the intake it starts. when it starts on the spray, it idles high till i unplug one of the tps pigtails and it calms down. and by high i mean around 2k. when it used to start on its own, it would run perfect. start right. and not have a problem. with it now, when its finally running and going through the tps steps and it calms down, it runs fantastic. no hesitation. no rough idle. but i shut it off and then it doesnt start again till i spray stuff in the intake.

so here goes:

full tune up
new tps
new cps
new fuel pump
have fuel pressure
have spark


im lost. it seems initial fuel is the issue, but i dont see how its not getting fuel if theres good pressure.

lastly, i noticed the little white thing that has to do with the fuel system(has two wires that connect to it and is bolted to the inside of the driver fender on renix vehicles) it gets really hot. it even got pretty warm while just trying to crank it a couple times a few minutes ago. what does that do again and how to tell if it works?

Shorty
August 30th, 2010, 14:37
it's an in-line resistor that's there to reduce voltage to the pump to help keep the pump quiet. It was installed in response to customer complaints concerning noisy fuel pump.

It should get pretty warm when it's doing it's job, as it's just a coil of wire to add resistance in the line, but you shouldn't feel it "hot" from just trying to start the vehicle. It is bypassed during the crank signal and shouldn't have any juice through it until you release the key into the "run" circuit.

You can "bypass" the resistor by jumpering the two wires together without any ill effects. The fuel system was originally designed without the resistor in line. The addition of it, again, was only in response to noise complaints.

old_man
August 30th, 2010, 14:37
Did you adjust the tps? Make sure the arm on the tps is on the correct side of the bellcrank on the throttle body.

Get it running, turn it off, wait a minute and what is the fuel pressure? It should stay high.r Turn the key on, you should here the fuel pump run for a few seconds and shut off. What is the fuel pressure then?

Shorty
August 30th, 2010, 14:46
40psi fuel pressure is actually higher than spec. when the pressure regulator is receiving a vacuum signal. Is it possible that you've got a damaged vacuum line to the regulator? Were the line broken, you would have closer to 40psi AND a vacuum leak that's leaning out your mixture (which would make things tough to start cold and cause an unregulated bypass to the IAC motor)

dick.breakey
August 30th, 2010, 14:48
the tps is on the right side. i havent "calibrated" it or whatever. i dont know how to. but it hasnt been since just when i replaced the tps. it just randomly started to happen.

i dont remember what the fuel pressure is in those cases. ill go out in a little bit and check.

dick.breakey
August 30th, 2010, 14:52
i did the spot spraying around the vacuum lines to see if the idle changed after spraying each certain spot. nothing. ive replaced some lines and inspected the rest. seem fine. i know its hard to just visual inspect them, but i thought the spraying would be good. i did it heavy enough to notice the change in idle if there was a leak though.

joe_peters
August 30th, 2010, 19:26
A large intake leak, resulting in a very high idle similar to yours, isn't going to respond well to spraying around--you can't introduce enough external fuel to enrich the mixture and slow down the idle.

Start at the intake manifold. Remove all vacuum lines, including the large line to the brake booster. Cap everything off. Any change? If not, inspect the EGR system, remove and plug it off if necessary. Any change?

I believe your problem is a large enough intake/vacuum leak that the mixture is just too thinned out to start the engine.

As pointed out, your FPR--fuel pressure regulator--should maintain 31 psi with vacuum applied to the regulator, and 39 psi without vacuum. Your high idle is robbing the FPR of vacuum.

Muddy Beast
August 31st, 2010, 00:03
Not sure if this will help, but I know on my rig (and apparently on many rigs in the 88-91 range or something) the fuel pump had a hose come loose, they came that way from the factory, so eventually the hose worked loose enough to eff up my fuel pressure. This ultimately ended in no start/hard start/random dying engine.

Because it's a known issue on your year, and you fit some of the possible causes, could be worth looking at.

dick.breakey
August 31st, 2010, 05:50
i dont have a clue as to how to get in and see if the bottom bolts of the intake manifold are loose. im a small guy, but this looks nearly impossible and from what others are saying, its a bitch to get to. whats the best way to approach this?

i agree with you Joe that its probably a large intake leak, which would have been the cause of the popping in the intake i used to get right? (i dont throttle it like i used to replicate that because i knew it couldnt be good for it)

i would like to try and tighten the bolts first and se how that works. the high idle thread (yes the big one you direct other people to, joe) shows exactly what it takes for me to get my idle down to the correct speed. if i may have some direction on how to navigate my hands and arms in there i would appreciate it.

dick.breakey
August 31st, 2010, 06:38
http://www.naxja.org/forum/showthread.php?t=975044&highlight=intake+manifold+tightening

i found this while searching for instructions on how to disassemble and reassemble the entire thing. if im just wanting to tighten them down again, is there a better way to handle it or should i go about removing the powersteering pump and getting in there that way? yall think its worth getting a friend in there to help or should i be able to do it by myself?

Shorty
August 31st, 2010, 09:58
I've had luck pulling the air box and fishing an arm and an extension with a u-joint under there. I also got the back couple from under the vehicle with a ratcheting wrench.

dick.breakey
August 31st, 2010, 10:17
i like the arm under where the air box is. ive got a buddy gonna come next week and help me. good thing this thing is a project and im not ina big hurry haha.

1990heepxj
August 31st, 2010, 10:32
the 2k idle is not a vac leak if it stops when you unplug the tps and plug it back in, a vac leak wont stop just cuz the tps is unplugged. i know what your talking about on the 2k idle mine did it befor when my egr transduecer was bad it would stall then when i would restart it it would run just above 2k rpm til i unplugged the tps or til i restarted it a few times in a row. some reason stalling seemed to be the cause.

dick.breakey
August 31st, 2010, 10:40
mine did it befor when my egr transduecer was bad .....


is this a fancy word for the egr or is is something separate to the egr im used to?

joe_peters
August 31st, 2010, 10:50
The vacuum transducer valve is part of the EGR system. It has three nipples--in and out 180 degrees apart on the top, and a third for back pressure on the bottom. The bottom nipple likes to burn away against the exhaust header.

EGR with vacuum transducer valve:
http://info.rockauto.com/getimage/getimage.php?imagekey=442940&imageurl=http%3A//info.rockauto.com/SMP/EGV608_FULL.jpg

Not used on the 87, introduced in 88, used through 90, 91+ the EGR system was eliminated entirely.

dick.breakey
August 31st, 2010, 10:54
could that be a possibility why it has a high idle? or should i worry about it after i make sure the intake is tight?

joe_peters
August 31st, 2010, 12:28
All or nothing. Vacuum leaks, intake leaks, EGR system malfunctioning--ALL of those are suspects.

TEST your EGR system, info from 90 FSM:

Warm the engine to normal operating temperature.

Operate engine at idle speed.

Check vacuum at solenoid vacuum source.

Disconnect the hose and attach a vacuum gauge to it.

Vacuum should be at 17 inches.

If vacuum is low, check the line for kinks, twists, or a loose connection at vacuum connector on intake manifold.

If vacuum is ok, remove gauge , reconnect the line and proceed to next step.

Check vacuum at solenoid output port.

Disconnect the line and attach a vacuum gauge to output port. Vacuum reading should be 0 at this side of solenoid.

If vacuum reading is 0, leave the gauge connected and proceed to the next step. However, if vacuum is present check solenoid/ECU operation with the DRB-ii tester.

Disconnect electrical connector at solenoid and note vacuum at output port. Vacuum should now be present at output port.

If vacuum is present, proceed to EGR valve test. However, if vacuum is not present, replace the solenoid. Test the EGR valve as follows:

Leave solenoid electrical connector disconnected. Note engine idle.

The engine should idle roughly or stall. If this occurs the valve is ok. If the idle does not change, proceed to next step.

Disconnect hose from the EGR valve and connect a hand vacuum pump to EGR nipple.

Apply a minimum of 12" of vacuum to the valve and note engine idle. If engine now idles rough inspect the vacuum line between the EGR valve and the solenoid.

If the idle did not change, remove the EGR valve and inspect the valve and the exhaust passage in the manifold for blockage, repair as necessary. If no blockage is present replace the EGR valve.

TRANSDUCER VALVE:

Disconnect the transducer vacuum lines and the back-pressure line (bottom). Remove the transducer. Plug the transducer output port. Apply 1-2 pounds air pressure to the back-pressure port. Apply a minimum of 12 inches of vacuum to the input port. Replace the transducer if it will not hold vacuum.

dick.breakey
August 31st, 2010, 12:43
i have the 89 fsm. ill have to pull that up so i can get pics. cause other than the egr its self, i dont know exactly what its talking about for th solenoids. but ill have to get a vacuum tester too. i love new tools haha

joe_peters
August 31st, 2010, 13:30
The Renix have a combination EGR solenoid and EVAP purge valve, should be on the driver's side fenderwell.

Good luck.