Engine no start, no check engine light on?

Tiny
GCRIDER99
  • MEMBER
  • 3 POSTS
  • 1996 CHEVROLET VAN
1996 Chevy Van V8 Two Wheel Drive Automatic 137k miles

In the morning, my van turns over but won't start unless I spray a little ether in it. For the rest of the day it starts fine and runs great. I tried adding fuel injector cleaner but it didn't help

Thanks
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,548 POSTS
Assuming you are not getting any error codes, it is a fuel problem.

Best approach is to have the fuel pressure tested with a mechanical gauge.

If OK, then I would suspect the cold start valve. It is a small injector that adds additional fuel on cold engines, it only operates when cranking and if not working will cause the no start (cold) you describe.
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
KNESTE
  • MEMBER
  • 2 POSTS
  • 1996 CHEVROLET VAN
  • V8
  • 2WD
  • AUTOMATIC
  • 240,000 MILES
I can be driving along fine when suddenly the engine is racing and acting like the transmission doesnt exist. This occurs for a few seconds and then all is fine again. Once when I started the van it died and I had to restart several times and had to increase the RPM to keep it running but when I got on the road the van acted like the trans wasnt even connected. I parked it and the next morning all was fine for about a week and then I had the problem when on the road at high speed but it corrected itself.
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
MHPAUTOS
  • MECHANIC
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Hi there,

Thank you for the donation,

i would first check fore any unresolved fault codes in the ECU, not all fault codes will set a MIL, also as a precaution I would get the transmission in for a test and report at by a qualified trans tech, to be honest, I don't think that I have come across problem like this, it sounds like a sudden drop of line pressure, but some tests may show up more, start here.

Mark (mhpautos)
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
KNESTE
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  • 2 POSTS
There are no fault codes showing up. Could you get me a second opinion as this is eratic and probably wont happen when it is looked AT
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
DBEYER
  • MEMBER
  • 1 POST
  • 1996 CHEVROLET VAN
  • V8
  • 2WD
  • AUTOMATIC
  • 124,000 MILES
Replaced fuel pump, filter, plug wires, dist. Cap rotor, cam pos. Sensor. Engine cranks but will not start. Pulled codes found PO306
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
PO306 is just a misfire on cylinder #6

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
  • 1995 CHEVROLET VAN
  • V8
  • 2WD
  • AUTOMATIC
  • 178,000 MILES
Greetings,

I really appreciate your website and making your knowledge and experience available to us shade-tree mechanics.

My problem child is my 1995 Chevy Beauville Van, 5.7 TBI, 4L60E Trans (I think), It's really in great shape and I plan to repair the rusted lower body panel and make her new again. But she's currently giving me fits.

I worked on it one evening, installing some fog lights. I ran my fused switch line to the a pin on the fuse block. Job was done, I shut her off, and went in for the night. She would not start the next morning.

The truck has it's original fuel pump (which I admit still could be the problem if there's not ENOUGH fuel pressure). However, when I jump the FP Relay, and crack the fittings at the base of the TB, II get a very healthy spray. If I pour raw fuel into the TB, she will light. I don't have a fuel pressure gage to check, but I believe the pump to be OK.

I have replaced all the fuses and Circuit Breakers. On two occasions the van DID start, but ran very rough. I attribute this to the FP Relay fluttering as I had a test light connected to ground and the relay activation lead. It flashed wildly and pulsed to the engine ignition. Eventually the engine would die, not to start again. This is what leads me to believe that this is an electrical issue.

She turns over freely. No known mechanical issues. I have + power to the injectors but they are not activating that I can tell through my stethoscope (long screwdriver to my ear).

I have swapped the PCM with a known good unit. I have also replaced the FP Relay. If I jump the relay, the pump runs at the same pitch as it always has. Sound just like the one in my 1995 Caprice. Are there any fuseable links or hidden fuses I should be looking for? Everything seems tobe in order under the dash. This has not been all cobbled up like so many old vehicles. It's all original and in very good shape.

So, assuming there is adequate fuel pressure from the pump, the PCM is good, all the fuses are good, the FP Relay is good, there is good gas in the tank, the battery is strong and connections are clean, what am I missing?

I am hopeful you can help me. My job is depending on this van.
Sincere thanks,

Chris Baker
Studebaker14@comcast. Net
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the fuel pressure and get back

FUEL PUMP PERFORMANCE

5.7L (VIN K) 9-13 psi
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
Will check that tomorrow. However, I feel the pressure is there. Assuming it is, after all of this, what would prevent the FP relay from engaging? It appears (if I got the right wiring diagram) that I'm not getting power to the relay or possibly the PCM, thus preventing the pump from running and the injectors from activating.

BTW, There is good 12VDC + at the injectors. Rechecked all the plugs.

So, if everything else is checking out OK, I guess my question is what would cause the FP relay to flutter? Could the pump put such a drain (dragging) that it would cause the relay to disengage? I would have my doubts, but I'm not the expert.

Thanks guys!
Chris Baker
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Its the computer that energizes the fuel pump relay and also drives the ground circuit for the injectors-recommend you check the wiring and also for shorted injector that's taking out the other


https://www.2carpros.com/forum/automotive_pictures/12900_fuel_pump_and_oil_pressure_sending_unit_1.jpg

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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
OK. But I swapped computers with a known running van of the same year, make and model. My computer runs that van fine.

Pardon my ignorance, but what would then be between (or before) the Computer under the seat and the relay and injectors that could cause this?

I've never seen anything like this. Also, I have great spark from the dist to the plugs.

Thanks for the diagram. Where would that test port be located on my van?

Truly, many thanks for your help.
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
RASMATAZ
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What type of fuel system do you have? TBI/MPFI/CPI Vortec? Not to familiar with vans-If its a vortec-you should be able to see the fuel test port when you follow back to the rear from the upper plenum
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
It's the last year of the previous generation of full-sized Chevy Van (boxy), So it is TBI--fuel is fed into base of TB and injected thru the 2 injection over the throttle butterfly.


https://www.2carpros.com/forum/automotive_pictures/277597_100_3140_1.jpg

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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
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Get helper to crank her over and look at the injectors are they spraying fuel in a cone looking shape-

The fuel lines is behind the TB follow the feed if there's no test port T the fuel filter
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
Already known. There is no fuel coming out. When I jump the FP relay, the FP runs and sound absoutely normal (I know, not a real indication of performance, but is't a start).

When FP is running, I can crack the fittings at the base of the TB and get a strong spray. What I've narrowed down is that the FP relay is not being activated when KOEO (key on-engine off) position. It should activate for approx 3 seconds as a prime to stat the engine. At this time the engine is supposed to start and the oil pressure sensor tells the PCM to continue pumping fuel. None of that is happening.

Thanks
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The computer doesn't control the OPSU-when the computer energizes the relay for 2secs it primes the fuel system-when vehicle starts up the OPSU powers the fuel pump by closing its contacts by oil pressure.

Check the pressure should be 9-13psi
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
Hi guys, Just got back inside. Very cold and snowing hard here in Northern Indiana. OK. Fuel pressure (if we read the things correctly) indicates just under 12 psi. I figure that should be enough.

So there is still no 2-3 second prime activity or injector pulse. Remember in my earlier posts, I swapped PCM's with a known working vehicle. Could there be a problem in the wiring harness? Any ideas of where I might start looking? BTW, there is no place in any of the looms that indicate melting or tearaway as if being too close to the exhaust of getting snagged on something. Also remember that she ran fine up to the point where I parked her, then she wouldn't start the next morning. Ans also remember the fluttering fo the FP relay when she DID start, but ran rough.

I'm not the dimmest bulb in the box, but I can't figure this one out. I honestly cannot understand what may be casuing this.

Is there anything under the dash, near the fuse panel that could be unplugged or something?

You guys are great. I am very releived to be able to bounce these troubles off of you. Hopefully, we can figure it out.

CB
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Remove relay from connecor-check wiring for power

At the fuel pump relay wire harness check for power on the orange wire-you should have it-if the fuel pump fuse is okay-

Now turn key to run you should have power on the dark green and white wire let me know-
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Friday, July 24th, 2020 AT 12:20 PM (Merged)
Tiny
STUDEBAKER14
  • MEMBER
  • 14 POSTS
Hi Ras, Orange wire is hot. Fuse is good. With the test light on the Green wire, it does NOT come on with key.

The problem has to be AFTER the key and BEFORE the fuel pump. I've just come in after checking EVERY electrical connection on the engine harness.

Also, all the connections under the dash, on the steering column appear to be intact and undamged.

Keep in mind, I have the insode engine cover off and a test light connected to the green lead so I can see if power is going to the FP. Plus, I can also hear the pump if it is running. It is almost as though there is not enough current to keep the relay engaged. I don't see that as possible as the Amp meter shows a positive charge when it did start, plus there is a high-power battery charger or other vehicle jumping it.
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Friday, July 24th, 2020 AT 12:20 PM (Merged)

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