Starting Issues

[Leadfoot]

Alright, Having issues, and have had issues since i bought it, but no matter when, hot/cold, day/night, etc, You have to pump the gas like a carb.. After you pump it a few times to keep it idling, its fine. I ordered an IAC valve for it but not sure if thats really the issue at hand. Anyone else had this problem? Sorry if this is a double post but i could not find a related topic.

[2scoops]

Are you allowing a few seconds before cranking to allow the pump to power up & pressirize? It took me awhile to figure out thats the way mine likes it. I turn the key on, wait for the fan to come on then off (that is my indication the ecu has done its systems check) then crank. Before, if I just cranked it would take awhile when cold, and if it was hot it wouldn't even start.

[ricksrb]

When I first purchased mine it would not start without pressing on the gas, I would not have to pump it. With out pressing on the gas it would just crank and crank. I finally realized that once it did start the idle rpm's was only around 600. I adjusted it up to recommended 900 and ever since it starts right up immediately. Only thing I could figure is it had to do with the Throttle position sensor.

[rocmoc]

Don't try and start the engine until you hear the fuel pump & fan noise stop.

rocmoc n AZ

[Leadfoot]

Don't try and start the engine until you hear the fuel pump & fan noise stop.

rocmoc n AZ

Yeah I always let the pump run untill it cuts off, same way with my fuel injected Harley. But it seems to Idle at about 900 already so Im kinda stuck.

[Guest Lenny]

Yeah I always let the pump run untill it cuts off, same way with my fuel injected Harley. But it seems to Idle at about 900 already so Im kinda stuck.

I'm going to think out loud here for a while. Pumping the throttle doesn't do anything except open the butterfly in the throttle body giving more air. It also, through the Trottle Position Sensor, tells the computer what the throttle is doing so the computer can adjust the pulse width for the fuel injectors to either give it more fuel or less. So it's either giving it more fuel or less fuel when you push the throttle. If it's flooded and you push the throttle, it gives it more air to offset the flooding and that could help make it try to run. If it's running too lean and you give it more throttle, the computer gives it more fuel to richen the mixture so it trys to run. If your flooded, you should be able to put the throttle to the floor indicating to the computer that it is flooded so it cuts the fuel, at least most car computers do this and the Trooper probably does too. But this only works while cranking. You could try putting it to the floor when trying to start to see if this does anything. I feel it is more likely not getting enough fuel. If it is lean and you push the throttle, the computer immediately sends the engine more fuel so when you quickly let up on the throttle it sees a richer mixture momentarily and trys to run again. The Idle Air Control (IAC) gives it more air and fuel to raise the engine RPMs when cold. if the IAC was bad, the computer wouldn't know it because there is no feed back. The computer just counts so many steps from the IAC closed position and the IAC is susposed to go there. But, the computer also gives it more fuel at the same time too so if the IAC was bad, I would think that you would be getting too much fuel slightly flooding the engine and you compensate for it by pumping the throttle. But if it was flooding, a running engine would probably blubber rather then just cut out. Again, I think it is more then likely too lean. If the engine is warmed up and running for maybe 30 seconds or so, the loop back feeds going to the computer tell the computer what the air/oxygen ratio is in the exhause (Oxygen Sensor in exhaust) and the computer will adjust fuel to match the air it is getting and it starts to run Ok. If the fuel pressure were too low or the fuel system is plugged somewhere like it s filter, the engine wouldn't be getting enough fuel until it runs for the 30 seconds or so, giving the loop back system time to innitate and correct for the low fuel presure and make it run OK. That makes me want to disconnect he fuel line just before the injectors and run the fuel pump to see if it is pumping a good quanity of fuel. Preferrably put a gauge on the disconnected line and a valve after the gauge so that when you run the pump, you can open the valve just enough so that the pressure in the line is maintaining about 50-55 pounds and then see what kind of flow you get after the valve. If the pump won't maintain this kind of pressure, you may have a faulty fuel pump. Run the pump by disconnecting the hotline going to it from the relay and run a wire directly to it from the 12v + of the battery. Then again think I would first just raise the fuel pressure at the regulator maybe 5 or 10 pounds and see what that does. Keep in mind that low fuel pressure caused by the regulator being set too low or a plugged fuel system could easily effect starting and not effect the engine once its running for the 30 seconds or so giving the computer time to go into loopback mode to correct for the low pressure. One other thing. The fuel pump has a one way check valve in it that prevents the built up fuel pressure, from priming, from flowing back, loosing the built up pressure. If the fuel pump pumps pressure that shows on the gauge but quickly looses it when it stops running, you may have to replace the fuel pump or add an inline check valve to do the job of the pumps bad valve. Hopefully this will give you some things to check and try. I think I'm thinking right but who knows, I could be thinking badly too. Hope this helps.

Lenny

[Leadfoot]

Lenny I was thinking IAC also, I ordered one from Jeff in Phoenix AZ, Should make its way to GA shortly (Lol). --Question: May be stupid to ask but could my snorkel be leaning the motor under initial start-up? The motor never misses a beat after initial start-up, like on or two pumps on the gas as its starting and its good. So maybe 1-3 sec. and its all-good.

Also----

Kinda off-subject but was messing around the house the other weekend, riding trails and what-not, went to the mailbox to check the mail and upon coming to the box, I didn't shift into first and stalled it out in 2nd gear easing upon the mailbox, Anyway, when i went to start it back up, it would not. Kept trying over and over again, pumping throttle, holding throttle, cycling the key, etc. And finally started after about 10 min of letting it sit... Never did it again but baffled me none-the-less. (It also ran like crap when it did finally fire up but after a few revs it cleared up) ?? Stumped.

[Kinarfi]

Your problem sounds vaguely familiar to when I needed a ring job, wouldn't start unless I towed it, then after it warmed up, it was good for the rest of the day, now when I start, as the pump is running I kick/tap the pedal and then stay clear as I hit the starter, but it seems to need the bump before the starter as if it were setting the aic, it starts, idles up and then settles down, I always figured it was just getting it's sensor information and dialing itself in for running. It may pay to run a compression test on it.

Kinarfi

[Leadfoot]

Your problem sounds vaguely familiar to when I needed a ring job, wouldn't start unless I towed it, then after it warmed up, it was good for the rest of the day, now when I start, as the pump is running I kick/tap the pedal and then stay clear as I hit the starter, but it seems to need the bump before the starter as if it were setting the aic, it starts, idles up and then settles down, I always figured it was just getting it's sensor information and dialing itself in for running. It may pay to run a compression test on it.

Kinarfi

What is normal compression on these things?

[Guest Lenny]

Lenny I was thinking IAC also, I ordered one from Jeff in Phoenix AZ, Should make its way to GA shortly (Lol). --Question: May be stupid to ask but could my snorkel be leaning the motor under initial start-up? The motor never misses a beat after initial start-up, like on or two pumps on the gas as its starting and its good. So maybe 1-3 sec. and its all-good.

Also----

Kinda off-subject but was messing around the house the other weekend, riding trails and what-not, went to the mailbox to check the mail and upon coming to the box, I didn't shift into first and stalled it out in 2nd gear easing upon the mailbox, Anyway, when i went to start it back up, it would not. Kept trying over and over again, pumping throttle, holding throttle, cycling the key, etc. And finally started after about 10 min of letting it sit... Never did it again but baffled me none-the-less. (It also ran like crap when it did finally fire up but after a few revs it cleared up) ?? Stumped.

I don't think your snorkel is any problem. Sounds like it flooded when you stalled it at the mailbox. Next time try putting the throttle to the floor which should be flood clear mode for the computer upon starting. With the pedal down, the computer won't add any more fuel when cranking, at least for regular cars it won't and probably the Trooper too.

Lenny

[Kinarfi]

What is normal compression on these things?

Readings should all be close to the same and I've seenfrom 100 to 150, but it depends on you tester too. Mine was home made. This will also check to see if the valves have worn and are not closing good.

Kinarfi

[Guest Lenny]

What is normal compression on these things?

You should be about 150psi. Normal atmospheric pressure is say 15psi and your compression ratio is about 10.5:1 This gives 157.5psi.

Lenny

[bruhaw]

You should be about 150psi. Normal atmospheric pressure is say 15psi and your compression ratio is about 10.5:1 This gives 157.5psi.

Lenny

I ran mine a few weeks ago just to have a baseline down the road. Has 620 miles on it and compression was 150PSI in all cylinders. Tested twice on each cylinder with about 3-4 cranks on each cylinder with all the plugs removed.

[Leadfoot]

I ran mine a few weeks ago just to have a baseline down the road. Has 620 miles on it and compression was 150PSI in all cylinders. Tested twice on each cylinder with about 3-4 cranks on each cylinder with all the plugs removed.

Will test tommarow, i have compression tester at work, Also got IAC valve in today from AZ, Will also install tommarow. I'll let ya know!

[Leadfoot]

Will test tommarow, i have compression tester at work, Also got IAC valve in today from AZ, Will also install tommarow. I'll let ya know!

Ok, Ran compression test, all cylinders within 4-5 psi of 150, Replaced IAC and starting problem still there, Ok heres the wierd part, and i need help with this once again.

Installed new IAC, let the motor go through the initial system test, fuel pump run, etc... Fired it up and the idle went to 1500 rpm, finally came down to about a 1000 and motor sounded really choppy. Revved it up a little and it acts like it wants to run away, it'll hold 2500 until you shut the key off. So i unplugged the IAC and everything went back to normal..???! So let me pick your brains yet again, what in the hell could be going on????

[Guest Lenny]

Ok, Ran compression test, all cylinders within 4-5 psi of 150, Replaced IAC and starting problem still there, Ok heres the wierd part, and i need help with this once again.

Installed new IAC, let the motor go through the initial system test, fuel pump run, etc... Fired it up and the idle went to 1500 rpm, finally came down to about a 1000 and motor sounded really choppy. Revved it up a little and it acts like it wants to run away, it'll hold 2500 until you shut the key off. So i unplugged the IAC and everything went back to normal..???! So let me pick your brains yet again, what in the hell could be going on????

I beleive that the computer closes the IAC upon initial install or reboot of the computer. It does this by sending electrical pulses to it to turn the motor. One pulse pre division of the motor. On initial reboot, the computer will send more then enough to supposedly guarantee enough pulses to close the IAC and the extra pulses just get ignored by the motor but the computer at least knows its closed or at least it thinks it is. Then when th engine is running, the computer sends reverse polarity pulses tothe motor to open it. The number of pulses depend on rather the engine is cold or warm or somewheres in between. YOu may try turning off the main power switch and back on after say 30 seconds and try starting it again. Do this a few timmes to see if anything changes. Maybe the pintle on the IAC was way in (open) when it was new and the computer didn't send enough pulses to fully close it but thinks it is closes. So it starts from partially open to more open resulting in higher revs. This is just a possibility. Maybe the IAC isn't installed just right and the pintle is sticking. you could try loosening it and re-tightening it. If the IAC is out but still hooked up to the wiring, when the key is turned on, the pintle should extend. But be careful, have someone hold a c-clamp over it to prevent it from opening too much or the pintle will come completely out. Generally you can put it back in by pressing it firmly but not always. It has to spin the motor to go back in. But at least this way, you could test to see if the pintle is extending upon key turn on. Is the IAC you purchaqsed a stock Trooper one or a substitute. If it's a substitute, it may not be compatable with the computer. If you have a friend with a Trooper, you could test it on their machine. You can also test the old IAC by hooking it up but not installing it and turning the key on with c-clamp being used of coarse. Is it possible that your throttle cable is sticking holding the butterfly open some. I recently changed my throttle cable just for the same problem. Some times it wold idle down and other times not all the way. If there is an air leak between the throttle body and the intake ports on the engine head or a hose disconnected, this would cause problems, so check for that. You could always blow air into the intake with a rag around the air nozzle and use soapy water to paint around everything to look for leaks. Your compression sounds fine but the choppy part sounds like a possible fuel issue to me. All you can do is just keep trying to think of things to try. If the MAP sensor which is on the aluminum intake manifold is defective, it could cause some problems because the computer may not be seeing the manifold air and thinking it needs to add so it opens the IAC. It all depends on how the computer logic is layed out. YOu might check with a knowledgeable car computer guy to see what they say or maybe just google it. For example look here:

http://www.google.com/#hl=en&sugexp=gsis%2Ci18n%3Dtrue&cp=32&gs_id=2t&xhr=t&q=New+IAC+but+still+run+a+way+rpms&pf=p&sclient=psy-ab&source=hp&pbx=1&oq=New+IAC+but+still+run+a+way+rpms&aq=f&aqi=&aql=&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.&fp=86611428d073bba9&biw=1685&bih=793

Hang in there we will get it resolves .

Lenny

[Leadfoot]

Lenny, Thanks for the pointers, I shut main power off and tried again, to my surprise it fired up first try, no pumping or anything, but the idle still way erratic, so tried again with the power shut-off, still fired first try but idles same, and also still acts like its in run-away, so i unplugged IAC again and idles fine and fired up first try. So Idk it just seems like IAC would be important, but it runs great with it unplugged... ? I don't know... Also checked for leaks with Carb. cleaner as it was running and found none.

[Guest Lenny]

Lenny, Thanks for the pointers, I shut main power off and tried again, to my surprise it fired up first try, no pumping or anything, but the idle still way erratic, so tried again with the power shut-off, still fired first try but idles same, and also still acts like its in run-away, so i unplugged IAC again and idles fine and fired up first try. So Idk it just seems like IAC would be important, but it runs great with it unplugged... ? I don't know... Also checked for leaks with Carb. cleaner as it was running and found none.

I don't use my IAC and if your running without it fine, just use the idle screw to set your idle rpms. All the IAC does is help control the idle when the engine is cold or when you turn the AC and simular things on, it maintains normal idle rpms. You don't really need it.

Lenny

[Leadfoot]

I don't use my IAC and if your running without it fine, just use the idle screw to set your idle rpms. All the IAC does is help control the idle when the engine is cold or when you turn the AC and simular things on, it maintains normal idle rpms. You don't really need it.

Lenny

Well I think we resolved it then! Haha I guess i spent 49 bucks on junk! haha Its all good though. Thank you Lenny for your help and everyone else. I guess the power shut off reset my ECU and it starts fine? Lol whatever works!