1990 W150 TBI Ignition Cut Off

1970FuryConv

Old Man with a Hat
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I have a 1990 W150 Power Ram 5.9/46RH. It has TBI with a return fuel line. It has SBEC as its computer. It has a Hall effect distributor with a 5 V return wire to the computer that allows the computer to calculate RPM and helps the computer to then calculate the amount of fuel to send through the 2 fuel injectors at the throttle body.

The truck spontaneously and unpredictably cuts off while driving - engine's hot. There is no coughing or sputtering. It just immediately cuts off. Then after waiting a few minutes, it starts up again and drives home like normal. I have a friend with a 96 1500 that is doing the same thing. I’ve been over the coil, the wiring, the distributor. I replaced the Hall effect sensor three times. I’ve replaced the SBEC with a rebuilt Delco unit. I replaced the fuel pump. Replaced the fuel filter twice. Checked all kinds of wiring. I’m coming to wits end on this. Has anyone run into this problem? How did you fix it? Thanks for any help, Ben

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I have a '96 3.9L V-6 that does the same...
I thought about pulling the ignition and putting a standard electronic type
in but haven't found a suitable conversion....



.
 
My 91 ran poorly after hitting a small pot hole, it was the VSS (vechicle speed sensor) on the side of the transmission near the tail shaft.
 
crankshaft position sensor or perhaps the fuel cutoff switch.There are also a bunch of fuel injection relays that will do this.In the Dakota world when this stuff starts happening to a pre-OBD2 truck 50% of the time it ends up in the junkyard because it is never fixed.Good luck
 
I have a '96 3.9L V-6 that does the same...
I thought about pulling the ignition and putting a standard electronic type
in but haven't found a suitable conversion....
If I go this direction, I've gotta figure out how to wire the computer out of the system. I've also got a replace the intake manifold and install a carburetor. I'll need smaller things like fuel pressure regulator and a carburetor kickdown assembly. I have thought of a magnetic pickup ignition system as a last resort, but only as a last resort because it turns my pickup truck back into a project. And then I don't have time to work on my Fury projects.

Of course, with multipoint fuel injection, your vehicle is going to be even more complicated
 
My 91 ran poorly after hitting a small pot hole, it was the VSS (vechicle speed sensor) on the side of the transmission near the tail shaft.
My truck did the same thing. I had to create a physical ground for it in the floor pan on the driver's side under the seat. Then I had to use a clip to hold the wiring in place so it couldn't move around when I hit potholes.
 
crankshaft position sensor or perhaps the fuel cutoff switch.There are also a bunch of fuel injection relays that will do this.In the Dakota world when this stuff starts happening to a pre-OBD2 truck 50% of the time it ends up in the junkyard because it is never fixed.Good luck
Thanks. The fuel injection relays, and perhaps a fuel pump relay, are good thoughts. I'll have to check and see if mine has a fuel cut off switch. My truck is old enough that it doesn't have a crankshaft position sensor. The computer uses feedback from the Hall effect distributor to calculate RPM. Of course, that all changed with the introduction of multipoint fuel injection, which did have a crankshaft position sensor. Let's hope my truck does not end up in the junkyard.:mad: It's the little things that kill. I put the engine in this truck. I set up all the pulleys and electrical. I put the transmission in the truck. I put the transfer case and driveshaft in the truck. I put both axles on the truck. I rebuilt the steering & steering portion of the front axle. I did the brakes. And now after 13 years it has developed this problem.
 
If the truck dies again, check to see if the auto shutdown relay is energized.Bad relay or bad distributor output to the SEBEC.I just thought of something else...check to make sure your torque converter is unlocking...there is another solenoid.Going backwards in time would actually be quite easy.The trans is hydraulic and the speedometer is cable.Going back to manual fuel pump is easy.I am thinking of doing all this to my Dakota.Thing runs perfectly, but there is no way to adjust anything.Runs so rich that it literally gets 10mpg in 2wd and nothing can be done with it.
 
If the truck dies again, check to see if the auto shutdown relay is energized.Bad relay or bad distributor output to the SEBEC.I just thought of something else...check to make sure your torque converter is unlocking...there is another solenoid.Going backwards in time would actually be quite easy.The trans is hydraulic and the speedometer is cable.Going back to manual fuel pump is easy.I am thinking of doing all this to my Dakota.Thing runs perfectly, but there is no way to adjust anything.Runs so rich that it literally gets 10mpg in 2wd and nothing can be done with it.

I replaced ASD, but no change. Could be circuit. ASD supplies power to everything from fuel pump to fuel injectors. What's frustrating is after a few minutes the truck restarts. I think something is getting hot and needing to cool off, but what?
Distributor output: I replaced hall effect sensor 3 times. Checked resistances to ground and to computer. Everything is normal.
Trans is 46RH. It may have torque converter, but it does not have wiring for lock up.
Electric fuel pump replaced in 2020. Manual fuel pump would eliminate one part of circuit to which ASD supplies power.
TPS and ISC are both setting codes for too high/too low voltage. Both of these would make it run less well, but my mechanic does not think they would cause the spontaneous shut down.
I think going back to carb and conventional electronic distributor may be the way to go.
 
So you have the 2 pin connector on the transmission instead of the 3?The ignition coil could be overheating I suppose. I would have suggested the sock on the in-tank pump but you already changed that.My truck actually did something similar last summer...turned out to be a dirty IAC valve.Your truck does not have that system.How are you getting the codes?Could the alternator be causing the high/low voltage?
It is frustrating when these old fuel injection systems start to be a problem.Very hard to troubleshoot.I have been thinking about putting a slant six in my Dakota, but will not fit with AC.
 
Have you checked the connector at the fire wall just to make sure something isn't heating up there?Might kill ignition run circuit.Very nice truck by the way.I had a 1993 V6 2wd that was a really great truck.I might think about the Holley Sniper to replace all your tbi stuff.At least then you would be able to monitor and adjust everything on the engine.Oops...there I go spending someone else's money again:steering:
 
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So you have the 2 pin connector on the transmission instead of the 3?The ignition coil could be overheating I suppose. I would have suggested the sock on the in-tank pump but you already changed that.My truck actually did something similar last summer...turned out to be a dirty IAC valve.Your truck does not have that system.How are you getting the codes?Could the alternator be causing the high/low voltage?
It is frustrating when these old fuel injection systems start to be a problem.Very hard to troubleshoot.I have been thinking about putting a slant six in my Dakota, but will not fit with AC.

Have you checked the connector at the fire wall just to make sure something isn't heating up there?Might kill ignition run circuit.Very nice truck by the way.I had a 1993 V6 2wd that was a really great truck.I might think about the Holley Sniper to replace all your tbi stuff.At least then you would be able to monitor and adjust everything on the engine.Oops...there I go spending someone else's money again:steering:
Connector at trans: no, it was 3 pin. The wire for lockup solenoid is cut off and and has been for 11 years+.
Ignition coil is an MSD unit. I could replace it.
Connector at firewall. It could be that. It could also be the ignition switch.
Holley Sniper: I'd rather get a carb and regular distributor, which would eliminate about half the potential causes. If I can't achieve reliability but just keep sporadically breaking down while driving, the truck needs to go. The truck was wonderful for 9 years. The last 2 years have been an electrical headache.
 
Yeah...it's too bad that these things can crop up.That roller 360 is a really good engine and would work well with points ignition and a Demon carb.You are already set up for an O2 gauge for tuning.I am not sure but I almost think that the front cover may have a block off plate where the fuel pump mounts, but perhaps not.
 
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Yeah...it's too bad that these things can crop up.That roller 360 is a really good engine and would work well with points ignition and a Demon carb.You are already set up for an O2 gauge for tuning.I am not sure but I almost think that the front cover may have a block off plate where the fuel pump mounts, but perhaps not.
I am thinking about a carb set up.
Need to ditch the AC compressor to install a decent intake. Need an idler pulley setup instead.
Fuel pump is 14psi. Need fuel pressure regulator with gauge and bypass. 5/16 supply and return lines.
Need electronic ignition kit.
Doable, but with nice Edelbrock carb/intake, cost over $1000. Considering.....
 
You could switch over to a magnum flat belt setup out of a junkyard 92 up for cheap and keep the AC. If your truck hasn't been converted from R12 you can still get a Sanden compressor that accepts R12. I am seriously thinking about buying a wrecked Tesla model 3:realcrazy:
 
You could switch over to a magnum flat belt setup out of a junkyard 92 up for cheap and keep the AC. If your truck hasn't been converted from R12 you can still get a Sanden compressor that accepts R12. I am seriously thinking about buying a wrecked Tesla model 3:realcrazy:

The AC condenser and hoses are long gone. Not sure about condition of evaporator.
AC has never worked since 2009 when I bought the truck.
I want to ditch the compressor so I can install an earlier aluminum intake with a centered thermostat housing. I have to look at how the compressor attaches at the TBI intake.
 
If you do not have to pass emissions, I would ditch that system. It is a pressure carburetor. Has very narrow adjustment range. Lots of those old electronics are just going to run out of parts, like the lean burn systems have gone through. IMO I would just make the commitment to change back to carburetor and normal distributor.
Even if you solve your issue with something simple, relay, broken wire, bad ground. How long till a sensor causes a problem, is it available? Did a sensor cause a relay or wire problem? I hate to say bail on the system, but everything earlier than 1996 OBD2 changeover is going obsolete. We are less than 4 models years from 30 years on the OBD2 format. All the OBD2 is multi-port leaving the throttle body setups even further behind, and not really compatible at all.
That engine is a very good piece. Has the swirl/fast burn heads and a factory hydraulic roller. The worst part of performance on that engine is the electronic fuel and ignition castrating it for emissions and fuel compliance.
My 2 cents
 
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