Was running, now starts up and dies

[88C/S]

I have an '89 CSX that doesn't have the VNT turbo. I have an SBEC FWDP modified, and that works fine and was running that for awhile. Have another SBEC that is socketed and changed the chip to run a boost button cal, in preparation for changing over to E85. The car ran with that cal for about a week. I put the FWDP modified SBEC back in to go to the SoCal meeting, because I don't have a wideband and figured the FWDP cal wouldn't lean out near 16 psi or so. That Friday evening, I noticed that the engine stumbled and the lights dimmed, for a second or so when taking a bumpy corner fast. Didn't think much about it until that Saturday, when the fuel pump didn't prime with the key in the on position. I checked all connections under the hood and put dielectric grease where I thought it would be needed. No change. Looked in the '90 FSM and it said if the HEP was bad, the ASD would kick in and not initialize the pump. Changed the HEP and the car started, but died when the rpms dropped close to idle.

That Sunday, was able to goose the throttle and get the car to idle at 1900 rpms or so, but it wouldn't drop to normal idle speed. Left it alone for a couple of days while looking at posts and saw that shadowjake was having a similar problem, but in my case, the car ran with either SBEC. Tried the other SBEC I have and got the same result. Put in another HEP and it would idle and then die. I was able to check the fuel pressure and noticed that when the idle was high, the fuel pressue would start to drop and then the engine died.

When the car was running at a high idle, the fuel pressure was around 55. I also noticed that at night, it was around 45* or less, that the pump wouldn't prime when it would prime during the day. Don't know what would cause this problem, just by changing out SBECs. Help. Thanks.

[1BADVAN]

any codes?
my van does that sometimes and i think it has to do with a barometric sensor or the idle speed motor.
hopefully you have some codes that can help narrow it down.

[88C/S]

the codes I could pull were 12, 66, 53, 55. 12 because while moving the power line from the battery, seemed like it kept the engine running and idling around 1000 rpms. so i made sure the power wire had a good connection in the lug. when I went to drive it, it stumbled when I pressed the pedal to accelerate. fortunately i was going slightly uphill, so just let the car roll back to it's parking spot.

[83scamp]

Well, there is no code 66, so not sure what you got there. 12 is battery diconnected, 55 is end of codes. 53 is the one that worries me. That's an internal logic module fault. It means the logic module portion of the SMEC failed the diagnostic test.

Per minimopar resources:

Possible Causes
Bad connection or wiring - Check the wiring and connections between the logic module and the power module. Make sure the logic module is getting all of its power feeds and that it is properly grounded (through the ground lug at the fuel rail). Clean and regrease any corroded connectors with dielectric grease and repair any shorts.
Logic module or SMEC failure - Replace the module.

http://minimopar.knizefamily.net/fault/code53.html

[2.216VTurbo]

^Keep in mind Scamp the codes don't end at 55 on the CSX VNT's. I'm chasing a 61 right now(baro fault tho I've bypassed it and replaced it) that throws a CEL asnd makes it hard starting when hot.

[83scamp]

^Keep in mind Scamp the codes don't end at 55 on the CSX VNT's. I'm chasing a 61 right now(baro fault tho I've bypassed it and replaced it) that throws a CEL asnd makes it hard starting when hot.

I didn't realize the VNT's went higher, sorry about that. Learn something new every day...:)

Although the OP stated it has a non-VNT turbo in it. Maybe that's where his problem is???

[88C/S]

Well spent time checking for continuity on the components I could determine from '89 & '90 wiring diagrams that are involved with running the car. None had a discontinuity. So for now, will need to do more research on why the ASD clicks about 1 second after the key is turned to the run position. The dash lights up and the radio comes on, but no hum from the fuel pump. When rotating the key to start, the starter motor turns the engine. The ignition switch was changed about 4 or 5 months ago.

[ShelGame]

Code 53 is just a checksum failure. You will get that code with some vendor cals. MP Tune re-calcs the checksum to remove that code. So, mine shouldn't have it.

The 53 doesn't indicate any other type of failure, just FYI. Regardless of what the books might say.

[88C/S]

Checkeld J2/DB wire at relays/solenoids and they have power. Grounded blue wire with yellow tracer at the diagnostic connector and the asd relay clicked.

[ShadowFromHell]

Sounds like a bad pump. My NY did this for a while. Would work, then wouldn't. Entirely impossible to replicated. Towed it home once, and it started in my driveway. Your going E85, so you need a new pump anyways.

- - - Updated - - -

You could verify its the pump when you are in a no prime situation by probing the pump power wires.

[88C/S]

The pump is new, but the old pump did the same. After probing all of the power leads and checking for continuity, I acted on a thought concerning the bulkhead connector. Took the lower part of the dash off, moved the fuse block to the side, and saw that I could wiggle the bulkhead connector a little bit. Crammed myself somewhat under the dash to see and found the connector with the power wire of interest and pressed on it. I was able to press it in a little. I put everything back together, and the pump primed with the key in the run position. The bulkhead must have come loose when I drove to the meeting with the Monroe Formula GPs destroying the 20 odd year old bushings. Quite a racket from them the rest of the way there and especially on the way back. So driving around town on bumpy roads moved the connector more just enough to not pass the power to the pump. Got bushing replacements from Johnny.