1993 J30 Running Issue

[RapidJim]

I have a 1993 J30 that hasn't run in 3 years. Drain the fuel and added new fuel. It started right up. Ran for about 5 minutes then quit. Could get to restart if i pushed the fuel pedal partially down and then died again and wouldn't restart. Checked fuel to fuel rail and it as there with good pressure. Gave up and tried it again this morning, same thing, started right off ran for 5 minutes and then it quit and wouldn't restart.

[fourdrinie]

Hate to keep repeating it....
clean, and/or replace the MAF sensor.....
a most probable cause

Keep us posted

[RapidJim]

Okay I cleaned it with MAF Sensor Cleaner, made sure it was dry. It started, ran a bit rough, let it run a bit, put it in gear to drive it, stalled, and now it won't even try to start. Not sure if I should wait till the AM to try again or break down and buy that expensive MAF Sensor.

[fourdrinie]

https://www.ebay.com/itm/New-Mass-Air-F ... Swvg9XT5Im

THIS ONE WORKED FOR ME

[fourdrinie]

Sorry, the above one doesnt fit your year, but find an equivalent

[fourdrinie]

there are a few 93 MAF on ebay for under $30

[RapidJim]

Well,this AM installed a brand new MAF sensor. Same issue. Started up fine, first attempt, ran for 5 minutes,, shut it off and now will not restart.

[fourdrinie]

sorry, that's the most common cause I have found for intermittent starting and stalling on these cars.

Since you don't have OBD2 trouble codes, you need to find out if the ECU is throwing codes to help you diagnose the issue.
You can look up how to proceed on this forum, or download the FSM, also available on this forum.

I have read that the temperature sensor switches on the front of the engine can throw a bad signal, telling it not to start..just a hunch...

you need to either replace parts at random with educated guesses, or see if the ECU is throwing a code to pinpoint the real error.

[RapidJim]

Pulled ecm and did code check, 12 which the manual says is the MAF

[RapidJim]

12 volts is present at pin E

[fourdrinie]

just a guess....give the time for the MAF to re-adjust the system....try restarting it a few hours later.....

[RapidJim]

Okay I will try that. I just completely checked the harness, have continuity from pin 26 to range wire at MAF and pin 27 to white wire at MAF, Also have 12vdc on B/W at maf and Grnd on Black wire at MAF so I am convinced the wiring is okay. Left battery un hooked for a while to clear ECM. Tried restart, fired right up, however within a few minutes it again died and would only fire up with messing with the foot feed, put it gear and died again. This is driving me nuts!

[fourdrinie]

I know you said you drained the fuel, however bad gas can do the same thing....run that new gas thru!!!

[RapidJim]

I will try that, however, not sure how bad gas would cause a diagnostic code. But at this point anything is worth a shot.

[fourdrinie]

I had the same issue a few years ago, after getting bad gas at an independent gas station....took awhile to run good gas through to eliminate the stalling...the car gave a MAF code...which replacing it with a spare did not help....had to run the bad gas mixture out by just racing the car in idle for quite awhile.

[fourdrinie]

how's the car running? pass all the the gas? lol

[RapidJim]

Same issue. I purged the take again, added 2 cans of sea foam and 5 gallons of fresh premium fuel. Working on it again this am. I still have the same issue. Starts fine when cold, idle starts decreasing after 5 to 10 minutes, then justr quits and will not restart. Still has code 12. I am almost to the point of junking it.

[fourdrinie]

i know you said in your first post that fuel pressure was good....did you test it with a meter?
I'd be interested to know when it starts to decline in idle after 10 or 15 minutes, does the fuel pressure decline or maintain normal pressure?

[RapidJim]

Maintains normal pressure. Ohms checked the coolant sensor, it checks good, even disconnected it after it warms up a bit and the idle jumps as it should.

[RapidJim]

I have even cracked the fuel line after it quits and there is all kinds of fuel coming back from the fuel rail.

[fourdrinie]

some random thoughts....
fuel pressure regulator?
when the car doesnt start, can you hear the fuel pump buzzing from the rear deck?

[macgiver]

mac , mystery huh , does indeed SOUND like a fuel thing , but ONE possible way to see if 'n your spark trickles down and fails (for some God forsaken reason ) - whearas IGNITION is dropping off -disconnect & remove a coilpack ,gnd brkt and re-connect w/small screwdriver setup / sparkgap - have helper see if spark stops before engine quits ??? GT 2/23/2018

[macgiver]

Coming back with another suggestion cause I own one Be completely ABSOLUTELY positive of NO restrictions in Air filter box inlet , most importantly NO restricted "snorkel" passages to R + L throttles ( if snorkel removed you can then chk remote possibility of cloggage dripping down from both crankcase "ventilation tubes into bores ) Hey I've heard stories of mice ,roof-rats , chipmunks crawling around inside eng. comprtmts , "sniff around" . Maybe some JAckazz (you know 'em ) shoved a rag there ,,, so they can lowball offer on your car ?
Here's the kicker - cause your talkin sellin it , and this won't cost too much ( $40-$60) TPS (throttle position sensor) is
"crunched in the ECM together with MAF (you have two MAF ,at least one good?) . TPS basically a variable resistor(a "Potentiometer" ) yet MAF is IC's on complex "board" so when CFM of Airflow from MAF doesn't Jive with the as "seen" throttle opening as reported by the TPS , and it's the TPS being bad a Code may definately show as MAF problem . Of course could be bad MAF which we figure you've eliminated , then leaves next the wiring to & from MAF or TPS to their respective downline connector destinations -chk those last. So , I'm coming back around here feeling "warm" on your 12 code you say is an MAF flag . Really shouldn't chuck the car until you have cross swapped a NEW/REPLACEMENT TPS and with BOTH your MAF's. Lastly - you don't really need the AIR-BOX sealed w/filter nor even MAF connected to AIR-BOX (MAF to snorkel yeah ) if 'n you can't be positive there's ABSOLUTELY no restrictions AFTER MAF . GT 2/23/2018

[RapidJim]

Okay, got some more tests done before it quit again. Fuel Pressure just over 40 book calls for appox 36., maybe my gauge, disconnect fuel regulator and it goes up to 48 psi, book says 43.4, roughly the same about of increase. The pressure does not drop before it dies and holds at 40 after it dies. One thing i did notice, is the fuel gauge does bounce some. BTW new pump.

Plenty of spark at a coil after it dies. No restriction in inlet box, makes now difference if lid on the box is on or off.

I haven't checked the TPS yet.

[RapidJim]

Okay something isn't right. According to the Service manual, wire code on the TPS is A- OR/L, B-Black, C-Grn. This connector is A-White/G B Red C Red/Bl. Either way, no 5 volts on C no ground on A, 12 vdc on B. Checked temp sensor 5VDC is there. Now I am really confused.

[RapidJim]

More info, door sticker says 3 of 92?????

[RapidJim]

Silly me, I did not know there was 2 plugs on the TPS, one with a pigtail and one without. The one with the pigtail is the correct one for testing. 5 vdc is there and so is grn and there is continuity from pin b to the ECU. Back to square one. Junk yard is looking real good right now, I just hate to be beat by a car.

[RapidJim]

Still only code 12.

[macgiver]

rapidjam yes two connections a pigtail AND conn. on body . Now that TPS has TWO simple switches (@isdle & @WOT)
PLUS THE most imprtant is the POTENTIOMETER aspect - this is the variable resister portion which really is #1 on TPS
problem check ,use multimeter (preferably Analog to see "fine" movements in the readings) your connecting the "center/slider " of the POTentiometer with EACH of the two "fixed" side legs side .Not always able to VERIFY 100% this way now -suggestion buy one , used or better yet NEW . Used -$60 , new $?? Glen 2/23/2018

[fourdrinie]

I was reading through some old posts regarding stalling issues:

I was having a simular problem with mine dying like that. It seemed to me that it would happen most of the time when I was off throttle, like at a red light or while coasting to get into the turn lane. It would not run rough or hesitate, the engine would just slowly die without me even noticing it was happening.My problem was a vacuum line was off. It was the line that ran from the EGRC-solenoid valve (on the middle of the passenger side of the engine) to the air intake duct. It had came out of the bottom of the air duct and if I had not been looking for a vacuum line being off, I would not have ever noticed it. It plugs into the very bottom off the flex elbow on the passenger side of the air intake duct.I put it back in and it hasn't died since. Your problem could be something completely different, but it sounds simular to the problem that I was having. Check your vacuum lines before you spend a lot of money, maybe you'll get lucky.