Engine Won't start,

do you lose the radio during this dies and wont restart, but has spark and fuel ? from another thread it was suggested the asd relay affected the injector signal, and the guy came back to say his radio fuse was the culprit ? easy check. 12v test light, inspect all the fuses with the key on and touch all the contacts for power on both of each fuse ? loose fuse could also perhaps be worth a try, and explain intermittant loss of injector signal? It is a theory.

The radio works just fine. Usually in the past if I let the truck sit for several days it will start.

Then you lose spark, or fuel pressure, what methods are you using to verify when it is acting up, I mean at that moment. Can you verify there is spark on enough cylinders to run it? and is your fuel pressure always in spec ? Then has rest pressure ? and drops some when cranking ? Does it try to start and then die ? But you say it will just stop running. you need to find what you actually have lost during the event. spark, fuel, or injector pulse.

And during the event, does it have power at both sides of all the fuses ? Have you inspected and tried relays in the power distribution center ? Please complete these checks when it is acting up to define the nature of the problem at the time it wont start.

If you have spark, and injector pulse signal, you may still have an injector issue. Try troubleshootmyvehicle. com There is a 3 page write-up of a case study where the injection system is tested and diagnosed. the spark was good on the case. The 4.3 in Izusu is included.

Yesterday, 02/07/2015 the truck started. How it started it important. When I tried to start turned over with no indication it would start. You could hear, good compression, but 100% dead. At about 7 or 8 seconds when I was about to dis-engage the starter, I heard a very faint attempt to fire like an old carburetor weak engine trying to come to life. I stopped cranking, I repeated 7 or 8 second attempts to start. The 5th or 6th time the truck started. It was rough for 2 seconds and then was perfectly smooth. It is running again. It has restarted several times nearly perfect. Perfect it would start nearly immediately. I would not have to crank the engine over for more than 1 second to start. It takes 3 to 4 seconds now. But, starts. I know the injector is not leaking or the pressure relief valve is not leaking because, during starting attempts, I have a habit of turning on power and waiting for the fuel pump to stop so it would start fast. After the initial attempt to start, the pump never needs to pressure up, the pressure is at proper rate 60 LBS. I have not checked the fuses, but, I don't believe a fuse will allow a 100% dead condition for a month, cause a hard start after sitting a month, then run perfect until the engine experiences a 100% death, as if the ignition was shut off and not start for a month.

When this weak start occurs, then improves, then runs, then further tries also take extended cranking time, Could a loss of injector signal be happenning? And why cant an electrical connection of any two parts be intermittant? Sometimes the things we know prove not to be so. To find out what is truly happenning, we must test. ..............I believe you have further defined your concern. now you must be ready with your tests, connected to run them, and make it act up, or wait for it to do it. Then observe your test equipment and see what thing is missing but suddenly cooperates. We do it every week or so on some POS for one reason or another. I once had a AMC/MOPAR morphrodited cherokee like that. With each truth I had to prove to the guy, all that had to be done. I had pleaded with him to believe me. A month of demonstrations later he finally wanted a spark module,(in his case) Then we fought the plug brand name issue, Then the injector pulse issue, each time, the same thing. Things he knew kept us from running the tests that were indicated. The part causing the most issues was recommended the first day, All the rest surfaced as I had to go thru every bloody thing else. In causal parts I found an additional $300 in no start issues, but he, in his case, had a processor issue, then sensors robbing voltage from his injector signal. Un plugging them all and showing him did not work, but I paid to get it to run for me. proving all that was true. Then I had the sheriff watch him tow it away. The tests can be found on that webpage, or in the mitchell database at the library. When you find the cause ? who can really say definitely without running them and leaving the test equipment in place.

I guess I deserved that lecture. I had not checked the fuses because I couldn't find them. What a strange place. But, I pulled each fuse. All have significant pressure and feel quite tight and secure. They did seem to have a silver plated tarnish. The Relays have excellent pressure also. It started nicely today. Have not driven it, afraid of getting stuck. Question for Dannyl if you are willing. I am aware that the spider SCPI injection is just absolute junk. It will have to be replaced at some time. Could that injection be the issue? Do you think I should just bite the bullet and get a MFI conversion kit.

I have read some discussion for that injection system having troubles, it sounded repairable, I thought. now I must ask if the dealer knows a correction for it. redesigning it but skipping that step can be a mistake. There could be better parts available through them and their techs may see it for repairs the most. They may be able to answer confidantly. I personally have not had the pleasure, but my experience tells me often the answers for that are on tune-up line at your dealer, and answers like that come with a few questions by them first.

The Conversion MFI is specifically designed for that engine. The problem can't be the poppets, as they leak and cause rough running, misfiring etc. as a general rule. When it dies again, I am going to inject propane in the engine and see if it fires. I suspect it will . See photo of the MFI injection with actual injectors at each cylinder. I spoke with the California Automotive repair bureau. GM had such a problem with the poppet injection, they extended warranty to 10 years / 100,000 miles. Unfortunately, I have a Isuzu Branded Chevy and it is beyond the 10 years. Calif ARB said, rebuilt injectors are not the solution, they are junk. Is there a controller board in the GM SCPI injection? When the engine stops it is as if the ignition was turned off. I am wondering if may be electronics related. What I don't understand, if it is electronics, why it is hard starting after it sits weeks then starts again.

When there is a fuel delivery problem and it dies but wont restart, you need to test and verify with experience, did I lose spark, fuel, compression or timing ? What ways can i test it, prove it, set up and monitor. when it stops running? why? what did it just lose? injector signal? If the manufacturer admits this and then has a run and hide policy till they all change owners or the warranty expires, all you can do with an unsupported system is ask for goodwill from the maker. If they want tests run by a dealer before helping you thats awesome. If they say it is not supported, then you have to either buy what they can get you or get parts from a u-pull-it type yard. Having all your readings and test results will help. having the test equipment attached when it acts up would help. Extended cranking and repeated attemps resulting in eventual misfiring start leading to eventual start and run indicates loss of compression. But all the cranking and sparking could lead up to a restart. so. what are the plugs like, whats the compression readins, whats the injector signal doing, is prime lost, is it bleeding off air first. I do not know but the dealer techs who could fix them after all that unpaid time may have your best suggestion.

(attempts)(Readings) excuse me. Like I say I have invested months in trying to help people and being they have their own diagnostic method and dont pay their bill, I just have to recommend appealing to the maker.

Having an armload of replacement components from the u-pull-it yard for swapping in and out can be helpful. But if you are not driving the one that breaks down? you need to be sure it is not tampered with in your absence, that I jave also seen.

Update. I started the truck today. It runs perfect at idle. It misfires when increasing the engine RPM. If I accelerate too quickly, the engine wants to die. All these tests were done while sitting in park and not driving. The vehicle was warmed up about 8 minutes before increasing the engine RPM. I brought the engine up to about 1500 RPM and kept the engine speed constant and the engine would mis-fire. I kept the the accelerator perfectly still.

that describes a lean condition.

sensors out of range do not always set a code in the processor's memory. after sufficient run time,and a plug check, you would be able to verify results of air/fuel mixture and how it is affecting your plugs.

once you determine which cylinders are misfiring, you can decide if you are losing a key element to that or those cylinders, and which one. and is it lean? or flooded. is it ignition miss? or do you need a new squid.

during the plug check is a good time to run your compression test and record your readings. are the misfiring cylinder(s) low on squeeze? Were they washed by fuel? or was it actually a lean condition for each one. Keep notes and record data so you can find the consistancy. That's the best advice for trying it at home.

My son has a 97 hombre also, low miles, new fuel pump and filter. This truck also started sputtering and would die while being driven like it was low on fuel or out. I filled the tank up and the truck didn't act any better or worse, sputtering while driving and dying while stopped. Made it home, parked it and I have let it set for 3 days now. It will not start just turns and turns but won't kick over. Ive checked the plugs and had a shocking experience with them so I'm pretty sure its trash in the injectors , since when I changed the fuel filter there was all sorts of crap floating in my container where the fuel lines were draining. I'm also just a shade tree mechanic, and don't have the snazzy tools for diagnostic tests. Other than changing the injectors I'm not sure where my next step would be

Use your google, pretend you have a blazer or eqivalent, with 4.3. look up your "spider injectors" or "poppets" There has been new info about this kind of system. There is another company that has a multipoint conversion, there is some spider injector discussion of the ball valves at their entry behind the intake valve. I recently did research time for CrisGrasser and saw this new info. You could look at the thread for his vehicle. search by his username, or I will see if I have that in recent activity. Yours cranks but wont start, first you need a spark test for voltage. there is an inexpensive tester that is volt adjustable made by" Lisle" parts and tool stores have them for 4 bucks. Then fuel pressure, fuel volume, fuel delivery. You can say its getting there...but in what measurement/ milliseconds/ amount/ what is the spray pattern quality??? This is why GM had to help longer on the spiders, and the aftermarket responded with a plan to make a different set-up. I will see if I have his thread 4u

see where purpleparrot has that MFI (multiport fuel injection) set up there in his posting for this thread??? after you test and research, you know what your tests reveal, one definite thing I proved recently is spark plugs can be the right part fit right and run, but A/C delco run better. I had a injector pulse timing out for antitheft. it would run then die. was non communicative computer, When the A/C plugs were in it, the rpms were higher, up to full rev for a few seconds longer than the MFR recommended plugs. It's not magic, its just the best plug. (opinion) sure, but thats enough evidence for me.

If you can filter the fuel, you can run the pump to get it out, clean, then back in. Then rebuild or replace everything thats full of that stuff. Some filtration is not good enough. you have to let it sit in a large pickle jar to see what I mean. then pour off the top. That garbage` is ending up in all your parts forward of the filter. then it cooks and becomes like black granules at the injector pintle, some injectors have tiny screens, and it sits in them, too. you can readabout injector science online, or watch u-tube vids about it. but they go from a conical spray, then with dirt and time diminish to a dribble even though they clickity all their worth, they just drip, or continue to drip. so back up to testing...... fuel injection rest pressure, very important. (hard or no start) but run the tests, you cannot just assume its enough. this is why codes are there, and equipment for testing is so wide a market. good test equipment is worth it. like a welder from Italy, or an espresso machine, or a fuel regulator from Bosch. anything less is crap and problematic. (opinion) but hey. dont want my little girls eating hotdogs and beans, when healthy food can be afforded.

It should be noted, that if your Isusu Hombre is the same as we are discussing in this thread, then your interjecting another MMY into this thread is Confusion, the preferred weapon of mans enemy. Another thread, with your own questions about a different rig is best responded to there. Then your type parts in use would be correct and not a pile of hooooooey for readers, thanks.

If you havent the foggiest, (injector humor) then researching your problems with your current symptom, and MMY. can be all the revelation you could need. thanks for reading. bye

Try. Maf or map sensors .if not spider ijection burning inside intake cover ??bad spider inj.?is it poping when it shutsoff