Sy dies after 30 seconds

B

bg_bls

New member
The problem started as an instant truck shutdown, with no warning, while I was DRIVING. It would start back up and I could go a few more miles and it would die again. So I parked it while I went thru the usual ignition probs.

I have replaced everything ignition related: distributor, plugs and wires, cap, rotor, coil.

Now when I start it, it will idle for 30 seconds really smooth then just die. I can start it back up and hold the rpm's around 2 grand and it will still die right around 30 seconds after startup.

I am going to find a FP gauge so I can see if that is a problem. Any other ideas??

Brian

P.S. Sy is stock with walbro fuel pump and upgraded IC pump.
 
SeattleSy#1255

SeattleSy#1255

Category 5 Conservative
Re: Sy dies after 30 seconds

fuel pump may be dieing

chip may not be totally seated or pin bent in the ECM (happened ot me)

map sensor dieing
 
B

bg_bls

New member
Re: Sy dies after 30 seconds

Walbro fuel pump is only about five months old. I could check the ECM, but I haven't opened it up before. The map sensor tested ok per the service manual, but I guess it could be intermittent.

Oh yeah, no check engine lights and no stored trouble codes.

I will double check the ECM connections and chip then report back.

Thanks guys,
Brian
 
RSpengler

RSpengler

Ghetto Fab Specialist.
Re: Sy dies after 30 seconds

I second the fuel pump dying, even though its not that old, those are pretty good symptoms of a dying fuel pump.
Rob
 
B

bg_bls

New member
Re: Sy dies after 30 seconds

What would I look for in Datamaster? Damn it, I don't want to change the fuel pump again....what a pain in the ass!

Brian
 
AUSyTyIN

AUSyTyIN

Unbusted $#it box
Re: Sy dies after 30 seconds

See if the vehicle is going instantly lean. That would tell you if the fuel pump is dying.
 
B

bg_bls

New member
Re: Sy dies after 30 seconds

I got a fuel pressure gauge and it holds pressure even when it dies. It is right around 38-39psi. When it dies it goes up to about 42-43psi.

Any other ideas??

Thanks,
Brian
 
B

bg_bls

New member
Re: Sy dies after 30 seconds

16Sy16 said:
Check base timing? Vac leak?
Click to expand...



Timing is at 0 with the tan wire disconnected. I just replaced all of the plastic vacuum lines with silicone hose.

I am lost here :(

Keep the ideas coming!! I appreciate the help.


Brian
 
AUSyTyIN

AUSyTyIN

Unbusted $#it box
Re: Sy dies after 30 seconds

So, the motor seems to be running fine, and then all of the sudden die? Does the whole truck die, or just the motor (radio, lights, etc)? What vac does the motor pull while it is running? Have you run datamaster? There could be a data error meaning signal loss somewhere to the ECU. Check all engine grounds? Check battery connections?
 
G

Gmoney

New member
Re: Sy dies after 30 seconds

Yea mine did the same thing, while I was driving then it would just die. I put a racetronix pump and wiring harness in it in July, and in October it went out again for some reason I can't explain. Hope that helps-good luck
 
B

bg_bls

New member
Re: Sy dies after 30 seconds

16Sy16 said:
So, the motor seems to be running fine, and then all of the sudden die? Does the whole truck die, or just the motor (radio, lights, etc)? What vac does the motor pull while it is running? Have you run datamaster? There could be a data error meaning signal loss somewhere to the ECU. Check all engine grounds? Check battery connections?
Click to expand...


I just went thru the whole truck before this problem came up and replaced everything I could think of maintenance related. Pcv valves, o2 sensor, vacuum lines, replaced intercooler lines with rubber hose, new thermostat, all ignition components, oil pressure sender, IAC, alternator, battery. The truck was running better than ever, but just not longer than about 40 seconds. The lights and radio stay on when the truck dies. Battery connections are good...do you know where all the engine grounds are?

I am going to take a shower and then I will log it with datamaster and post it up. Maybe someone will spot something I didn't.


Brian
 
AUSyTyIN

AUSyTyIN

Unbusted $#it box
Re: Sy dies after 30 seconds

No clue on the engine grounds are, never had to look for mine. Should be fairly easy to spot. Good luck.
 
Deanzsyclone

Deanzsyclone

New member
Re: Sy dies after 30 seconds

RSpengler said:
I second the fuel pump dying, even though its not that old, those are pretty good symptoms of a dying fuel pump.
Rob
Click to expand...

Yah also I don't believe a dying pump would show any code?
 
AUSyTyIN

AUSyTyIN

Unbusted $#it box
Re: Sy dies after 30 seconds

Is it me, or does anyone else thinks he has major data line issues? How can he have boost with no engine RPM?

In the same frame, his motor instantly goes from 700 RPM, to 0, engine temp riases from 105 to 270. The IAT is jumping around, etc.

The error occurs when your truck goes into closed loop. Me thinks you have an issue with your ECU. Anyone care to coment on my thoughts?
 
B

bg_bls

New member
Re: Sy dies after 30 seconds

16Sy16 said:
Is it me, or does anyone else thinks he has major data line issues? How can he have boost with no engine RPM?

In the same frame, his motor instantly goes from 700 RPM, to 0, engine temp riases from 105 to 270. The IAT is jumping around, etc.

The error occurs when your truck goes into closed loop. Me thinks you have an issue with your ECU. Anyone care to coment on my thoughts?
Click to expand...


Anybody second this theory? I just don't want to go order a new ECU and that is not the problem. Any other ideas before I pull the trigger on the ECU?

Thanks for your time,
Brian
 
VermontTy

VermontTy

Support Our Troops
Re: Sy dies after 30 seconds

The grounds on the engine are.....
  • 2 wires on the first driver side intake manifold stud just behind the alternator; 16ga (or so) insulated wires. I believe these two grounds are for the O2 and ECM circuits. Let me double check and get back to you in a few mins.
  • 2 wires on the backside of the drivers cylinder head; they are braided ground strap.
  • 1 wire on the backside of the passengers head; the main battery ground; battery ground also attaches via a plastic connector to a grounding point on the passengers frame rail between the upper shock mount and rad. support, and it also goes to a connector that connects to the headlight wiring harness. Both of these grounding points are the same insulated wire.
  • Above the A/C heater box; a 10mm head sheet metal screw. Insulated wires here too.
FORGOT ONE : EDIT

  • On the radiator support above the passengers side headlight; another 10mm head sheet metal screw. Probably for headlight / fog light gnd though.
Someone butt in if I forgot one. As I said, lemme check those on the intake manifold to see if they really are the O2 and ECM circuit grounds.
 
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