Jeepster hitting but not running

[chimp koose]

Where is WAYNE ?

[58 Yeoman]

This is coming from someone who knows NOTHING about FI and puters...have you checked to be sure you didn't eliminate the wrong colored wire? Say, dark brown as opposed to brown?

I wouldn't even be as far as Joe is if that was mine.

[GPster]

I still haven't changed the module to the new one. If this doesn'tdo it I have narrowed down the things that aren't working on the fuel injection side to the module wires to the computor and the computor terminals themselves. The only way I can figure doing that is checking each wire for continuity from terminal to terminal. I'm only going one step at a time because the Jeepster has a narrower cowl depth than the donor and I'll have to drop the ECM  back down to get to the terminal strips. I didn't cut any of the factory wires that I left in the harness but looking over the wiring diagram as a novice sure left some questions. There doesn't seem to be any standard color for ground. Some grounds are black and some are black with a white tracer. Getting into tan wires tah with white tracer is power from the computor to power the fuel pump circuit but you get down to the ECM there is a tan/white wire that is an engine ground. There's also a tan/black wire that is a ground for the ECM where you'd think that they could have used black/white. Well I know it has ignition because it will run on prime and now I have got the injector to open an spray gas. It's not like I have bought plates and insurance for it. GPster

[GPster]

I still haven't changed the module to the new one. If this doesn'tdo it I have narrowed down the things that aren't working on the fuel injection side to the module wires to the computor and the computor terminals themselves. The only way I can figure doing that is checking each wire for continuity from terminal to terminal. I'm only going one step at a time because the Jeepster has a narrower cowl depth than the donor and I'll have to drop the ECM  back down to get to the terminal strips. I didn't cut any of the factory wires that I left in the harness but looking over the wiring diagram as a novice sure left some questions. There doesn't seem to be any standard color for ground. Some grounds are black and some are black with a white tracer. Getting into tan wires tah with white tracer is power from the computor to power the fuel pump circuit but you get down to the ECM there is a tan/white wire that is an engine ground. There's also a tan/black wire that is a ground for the ECM where you'd think that they could have used black/white. Well I know it has ignition because it will run on prime and now I have got the injector to open an spray gas. It's not like I have bought plates and insurance for it. GPster

[kb426]

Joe, this might be worth reading:
http://www.justanswer.com/gm/4gnnl-1988-s10-tbi-no-fuel-spray-injector.html

[GPster]

Joe, this might be worth reading:
http://www.justanswer.com/gm/4gnnl-1988-s10-tbi-no-fuel-spray-injector.html

Thanks for another lead. I've missed that on . I usually stay away from those once that pop-up the name of a guy ready to answer your question because there always seems to be a charge involved and the answers aren't that good. I think I've seen the post from that guy with that problem on the S10 Forum and on a GMC forum.and when they run long like that it's hard to know if they've fixed anything because so many questions get lumped together you don't know what the answer is for and with 5 years passed and no Thank You's you don't know if it got fixed (I'm getting tired and can't even make a sentence). I'll look at it again when I can make sense of it. GPster

[kb426]

I found this:
http://www.73-87chevytrucks.com/techinfo/TroubleshootingTBISystems.pdf
https://ask.extension.org/questions/160417

[wayne petty]

start with digital page 46...   i don't recall if 87 and 88 use the same computer connector.. that would be the ONLY difference between the systems up to 1995.  actually. OBD2 systems are based on OBD1 systems..

http://www.73-87chevytrucks.com/techinfo/7387CKMans//Fuel_Emissions/X8836_1988_GMC_Light_Duty_Truck_Fuel_and_Emissions_Including_Driveability.pdf

you will want to print page 50 thru 54..

if you still cannot get it to work..

pull the harness off.. print the proper harness diagram  and ohm each wire as you go along..


i would also want to check page 108 and 109...

you will have to have printed pages 125, 126, 127 for your 2.5L  

several copies of page 135...  mark the pages up with what you measure on that circuit... scan and post it.

well... my computer has locked up on that file.. its my computer..

if all else fails.. and you now have a manual with more info than is in my head.. .

ps...  engine off... grab throttle lever.. open slightly, wiggle.  got shaft to bore wear..  it will effect how the engine idles...

if you have throttle shaft bore wear.. i can describe how to fix it your self for not a lot of money..  it does require getting a engine rebuilder to sell you one 0.375 K liner thin wall valve guide.  you will need a Letter Y drill. 0.404..   you must loosen the throttle plate screw only slightly.. it will bind when it gets to the damaged threads.. don't try to force it out.. use a dremel or die grinder.. even a diamond file to remove the damaged section of threads.. turn the screw back in.. take a fraction more off.. then see if you can get it out..  this allows you enough screw to mushroom over when reassembling the unit.. the screw size is 2.5M x .45 x 8mm special large pan head. yea.. right. ask for that at the hardware store..

drilling the throttle shaft bore to .404.. hose clamping the thin wall valve guide to a 3/8 wooden dowel to allow you to dremmel cut a section for both sides ..  drive it in... grease the shaft..  work it in..  if its too tight.. i hope its not.. you can perhaps find a 3/8 valve guide reamer set in the tool box.. drive the burnishing tool thru with lots of grease..  that should get it to size.

shaft. .372. Y drill .404. .375 liner .0.030 should give you around 0.01 or .02.. nice and tight..   but a sloppy throttle will usually not create a NO injector spray..

i would look at the Cranking circuit described... so the computer knows you are cranking the engine.. it sets the computer in starting mode..

i would also want to check the ignition module or hall effect.. some of the 2.5 motors had a hall effect module on top of the shaft.  its all covered hopefully above..

please try not to go probing things.. with other than a computer safe test light.. you can damage the drivers circuits..

if you need more.. i actually have a 1986 S 10 manual kicking around here some place..  that knowledge is all fuzzy as to what year things changed..

oh great.. another wall of text to skim..  and misunderstand.

this is my favorite image from the 86 manual



http://i.imgur.com/TCrpa8p.jpg

[Rrumbler]

I have been following along with this wishing I had something to contribute that might help, but I have no direct experience with this stuff.  However, something that happened in a 1989 Chevy Dually I had keeps coming  to mind; it is probably not relevant here, but just some anecdotal information that you can lay away on the corner the virtual mental work bench in case you need it.  

That '89 was a top line truck for the year, and had all sorts of automatic stuff on it, along with most of the safety features of the day.  One day, it developed a bad case of gremlins that I was completely mystified with; the a/c would change temps or functions without my input, the radio would change stations, it would just stop running, and then start right back up when I turned the key, and a few other less obvious things. One day, it just stopped as I was sitting in line at the dealers for a completely unrelated reason, and the service writer who came out to see me told me they knew just what was up.  They towed it into the shop, and fixed whatever I had brought it in for, and fixed the gremlins as well.  It turned out to be a physically broken brake light switch.  There were a number of features that the switch had to do with, such as cruise control, anti-lock brakes, something with the throttle controls, and with the broken housing on the switch, the contacts in the switch were loose and moved around when the brake pedal was moved.  Since all of those functions were involved in the ECM, they caused incorrect responses in other functions when they occurred.  A new brake light switch cured it all.

What I took from all of that mess was: make sure all connections and devices are sound and tight in vehicles with computer controlled functions; one little misstep can cause all sorts of weird reactions.  Like I said, not particularly cogent here, but one of those little things to keep way back on the edge of the virtual work bench.

[GPster]

Well, I seem to be in a more rested state of mind today. Went with my wife to a breakfast meeting today. The meeting was with people that she went to high school with and this year everyone is catching up with each other in anticipitation of their 50th class reunion. I graduated in New Jersey so I don't know any of these people but the meeting was at a Shoneys so I could keep the breakfast buffet in mind.We spent a few hours after that driving and visiting friends and when we got home at 4:00 it was time for lunch (I'm diabetic) . I read the sites that kb426 left for me this morning before leaving and the factory style of service advice is easier for me to follow so that gave the day a more relaxing start. Thanks . Rumbler I have had the same realization and I checked my revised (with all the wires and components that I'm not using whited-out) to see how many of the component I'm using might have ties to the ECM. The brake light switch was one because of it's N.O. contacts. They are tied in to the ECM with the converter lock-up . Also the switch on the power steering pump that ups the idle speed. I don't think I'd be wrong in guessing that they would control a running engine, not keep it from running. Wayne I'll be glad to start reading those pages and I'll see if my wife can make me a book of them. I imagine that they'll be of the text book style like what kb426 gave me the lead to this morning. Looking at Hayes manuals doesn't separate things by years so you can't always tell what to check on what year/model. It gets particularly fuzzy around that Halls Effect Switch (which I have) one place says that it eliminated the use of the R terminal of the Module. I kept looking to see if someone eliminated the switch and hooked up the module's R terminal. Well maybe some day this manuscript can me put to rest. GPster

[GPster]

Well, the latest update. Spending time looking at the manual that Wayne steered me to  it became apparent that all of the circuit checking revolved around a Noid lamp.  I have already discovered that the Model 700 TBI is somewhat of an oddball because of it's age and the fact that it has a single injector so none of the kits has the correct lamp for the injector's harness.  Nobody that I know has the right lamp in the back of their tool box so it's time to "bite the bullet" and buy one. Checking on Google the only ones that showed up were Bosch and the only supplier that I found was Tool Discounters and they were priced at less than $10.00. I bruoght the item up on the monitor and asked my wife to buy it (she's better practised at that than I am) it for me. Immediately got a Thank You for sending them an order. In the next 10 minutes I got the acknowlegement of the order. With-in a half an hour a message that shipping as specified (cheapest) would be over $12.00 (for a $10.00 lamp) and the order would be shipped in 7 to 10 days. Oh well! Because of the up-comming wait I decided to read some more. The factory wiring diagram gives incomplete details (and the wrong wire colors) for a little something that reading alerted me to. When the engine is trying to start the ECM goes into the "crank" mode so that the injector doesn't look for all of the "running" signals. When the starter is energized the ECM goes into "fail safe" mode. The wiring diagram shows how that might happen but the wire is not the color they indicate it is. The  ignition switch powers a pink wire and on it's way to the starter's solenoid it passes through the fuse box and energizes a 3A "crank" fuse going to a purple/(not)white to the ECM. The only purple/white wire going into the ECM harness comes off of the ignition module and the diagram doesn't show any (although there is one) plain purple wire. There is continuity between this purple wire and the purple wire that energizes the starter and nothing smokes so I think I.m right. That much sorted out I decided to put th NEW module in the distributor like I thought about doing  5 days ago.  Cranking the engine showed a little wetness on the TBI's butterfly (but it also appears that the top "O" ring on the injector is not sealed). No start. Primed the TBI. No start. One step backwards, I must have messed up putting the module in. Oh Well! I write all this down as a diary of what I've done. It's purely for you're enjoyment. No pictures GPster

[kb426]

From long distance, all I can do is cuss some for you. I'm pretty good at it though. The diary is a real good idea.

[UGLY OLDS]

I think that I found a photo that sums it up :    

Bob...

[GPster]

A guick question before I stumble/fumble into a repeat step. I mentioned that  I noticed gas leaking around the injector in the TBI. I removed it and got it free (to rattle) but because it was a questionable fix I did it in a questionable way. I re=used the old "O" rimgs around the injector. This injector fits in a gallerey and only has two "O" rings, one at the top and one at the bottom and after the injector is pushed down into the gallerey it just has a clip and a single screw to hold it there. The "O" rings weren't cut or mis-shapened but they were hardened enough that they made it hard to push the onjector down into it's gallerey. I ordered new "O" rings from (tomarrow at 8:00) NAPA but I wonder if there should be some kind of lubricant put on them to make things go together easier. Everything is clean and not damaged and I don't think there needs to be any sealant (only 13#psi). I think that the problem is mostly that if everything went together easier it would seal as intended. ? GPster

[Rrumbler]

It's always a good idea to lube O-rings unlaess there is some caveat aginst it, both for ease of inserting in a groove, and for helping them seal; I use a silicone grease, Sil-Glyde.  Don't get overzealous with the grease, though, just slick the O-ring up with it and leave a light film all over it.