Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have a 96 c1500 with a 5.7l engine, with a crank no start issue. Brief history, This is a new factory GM motor not a reman with approx 200 miles on it. New fuel pump, new dist, new Mpfi injectors, new crank and cam sensors, IC sensor, TPS, etc. Thing was running great, crank it up 1 morning and went inside and when I came back out it wasn't running tried to restart and all it would do is crank over. I have confirm spark all the way around even put on another new coil just in case other was weak, getting 61 psi fuel pressure, it is holding pressure at 55 for more the 5 min, pulled and check dist, cap and rotor, reset engine to TDC reinstalled dist cranked it over and reset engine to TDC rotor is back at # 1 cyl, so do not believe it jumped timing. Only think I have not physical check is the injectors actually spraying fuel, which I will do asap already have peallum removed. Any thoughts would be greatly appreciated. I am a DYI guy with a decent knowledge base mechanically but This thing has me about whipped. Thanks in advance DW.
Something else to think about which engine swaps is that wiring harnesses are sometimes damaged in the process and grounds aren’t always connected properly.
Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
Should of seen if it would of ran on alternative fuel before pulling the intake. Should of shot brake clean in the throttle body. And possibly your gas is bad and won’t combust??
I have check all the grounds they are good even recleaned surfaces for good contact as well. Yea it would have been nice to install a whole new wiring harness. Thanks
My next step, and I'm checking to see if any one of the injectors is sticking open. This was suppose to be a new AC delco Mpfi set, but I did get it off of Ebay so I am giving it the once over. Thankd
simperfi84 wrote: My next step, and I'm checking to see if any one of the injectors is sticking open. This was suppose to be a new AC delco Mpfi set, but I did get it off of Ebay so I am giving it the once over. Thankd
The one thing I haven’t seen you mention that you’ve tested is for injector pulse. You need to verify that the ecu is controlling the injectors.
Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
That's correct, I have not tested injector pulse as of yet, that is indeed my next step. I just have not had the chance to do so. I will post my results as soon as I have them. Thanks.
Make sure you have voltage at the wire on all injectors. You can easily check with a power probe on the most easily reached injector. You may have a blown fuse to that circuit and it powers all of the injectors. When swapping engines somethings chaffing happens and shorts to ground. If fuse blows instantly when you try to start it it will have a short to ground. Simply put your Voltohmeter to continuity to ground on that fuse and wiggle wiring harness until your short to ground goes away.
I read earlier that you tried the brake cleaner into intake? Did that allow it to start? IF if did and its clearly a fuel related issue and we are on the right track. if you have voltage on the pink wire then put a test light in place and see if you have injector pulse. A lot of guys forget to connect the ground on the back of the cylinder head. just a thought keep us posted
UPDATE!!.
Ok this is where I am at on my truck. First let me clear something up, one of the first things I did was to try starting fluid, and engine would not start. Which put me on the spark Track. Now I have confirmed without a doubt that I have spark, I have good fuel pressure and I just got through test the injectors. I have power, I have pulse and I physically pulled each injector and verified all of them or pulsing and spraying fuel. All of my grounds are good, I have checked a couple of cylinders and have good compression but I will go back and check all 8 cylinders. So I am at a complete loss here it should start or at least try to fire, We have all the ingredients. fuel, spark and air. I am open to any advice. Oh yea, no leaks with the spider system holds pressure and I physically check regulator, base and nylon lines. Thanks Everyone.
Good conversation and ideas folks. I'm not convinced all the ingredients are in place.
So, all the while after this no start, you did some compression tests. Were those spark plugs dry, or wet with fresh fuel? It's very possible all the cylinders are washed. Does the engine oil dipstick smell like raw fuel?
If the engine was previously running, it would be hard to condemn compression and ignition timing. Although it's possible, If a distributor was 180 deg. out it would still provide a backfires which would indicate fuel and spark. Try cranking the engine with the Distr. Cap off, does the rotor turn?
If you say your injectors are spraying, then the plugs should be wet, if they are dry, the intake valves aren't opening (snapped camshaft). Unlikely on a new engine, but highly possible if certain tolerances were not adhered to during building, or a bum shaft.
You checked the fuel pressure it was 61 psi, put the gauge back on and crank the engine, if the injectors are opening you should see a pressure drop, about 5-10 psi then recover back to 61 psi.
If you have any sort of spark whether it's timed or not with fuel, its gonna backfire sooner or later.
While cranking with a spark plug in the coil wire you have continuous spark? Ground the plug btw.
Ok following that logic, I did install new cats with the new engine but kept old muffler, I also pulled the distributor to check for any damage reinstalled it and after several cranking cycles reset engine at TDC and checked rotor placement and it was pointing at #1 cyl, however my mind keeps going to the timing thought. I will check compression as soon as I can. And keep ya'll posted. Thanks for your input.
Just remember though, when the rotor is pointing to the #1 cylinder, it could still be 180 degrees out on its exhaust stroke. #1 cylinder needs to be at the top of its Compression stroke. Use the spark plug out and the thumb bump test to verify its the compression stroke.
Weycraze,
Following along with your thoughts, First yes engine had been running fine, no misfires, no codes, and I had been watching fuel trims and the trims were good. I started truck one morning as I always did and went back in to finish my coffee came back out and truck had shut off, we t to restart and that is were we are now., my initial thought was timing engine seem to crank like it was out of time. I popped the dist cap off and crank engine over and rotor was spinning as it should. Check spark and fuel. Then I pulled dist to check gear and any other damage. Change rotor and cap, swap both cam and crank sensors I had all this on hand so why not.. then we got into more in depth testing. I spot check for compression and (YES the PLUGs were wet.). I have confirmed good continuous spark. I have confirmed all 8 injectors are opening and closing, and we have good fuel pressure. (New Delphi fuel pump) pressure on other was around 55psi and fuel gauge was off, cheaper aftermarket, that's why I chose to swap it out. Its sounding more like a flooded engine in which case I would like to know what caused that. My school of thought on timing and compression is while both are possible, very unlikely being this is a new engine. But I will do a full compression test ASAP. and recheck timing issue. It has taken me nearly a year to get this thing back on the road, after engine install I had issues with tranny, so installed reman. While working on all of this when I could, We had a visit from Hurricane Michael, that brought all the work on the truck to a halt. We are still digging out from Michael down here. Good news is if this turns out to be a internal engine issue it has a warranty. I will keep ya'll posted, and thanks for all the help.
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