SES Codes, running rich and stalling

[former520]

I am having some trouble with running pig rich and having rough running and hesitation.  If I get into it, it feels strong, but just cruising feels like it is struggling.  Lately (since I changed plugs) it is throwing a plume of fuel smoke when I let off the throttle to decelerate.  It is worse if I was just accelerating.

I have been getting a consistant SES Light when I decelerate after warming up.  I get codes 24 and 43.  From my searching I have been lead to believe that 24 is a VSS code.  My truck does not cruise or a odo that goes to 6 places.  I was under the impression it would not have VSS.  The speedometer does not work in this truck.  The previous owner swapped transmissions and the TH400 in is longer than whatever was there and the cable does not reach. 

43 looked like it was a knock sensor.  That I am figuring may be caused by the rough running from being rich.

Anyone have any ideas about where I should start to look?

87 350TBI Reg Cab, TH400, no cruise or power anything, AC

[VileZambonie]

Pull the vacuum hose off of the EGR valve.

[former520]

I disconnected it at the harness and left the vac lines attached.  Mrs. says I need to eat dinner before I can go try it.

While we are on the exhaust system...  I keep having the rubber pieces for the smog pump keep popping off giving me exhaust leaks.  Does anyone know what the size and pitch of the hard lines coming off the exhaust manifold?  I would like to stop the leak until I get to fixing that system.  One thing at a time.

[topp]

87 TBI does have VSS.

It's a sensor on the back of the Speedo.

[former520]

So there is a fair chance that I am going to need to get a speedo cable to give the computer what it needs...

[topp]

So there is a fair chance that I am going to need to get a speedo cable to give the computer what it needs...

I believe that you would need the cable or the truck is gonna think it's going 0 MPH at all speeds...

That would be where I would start....

[former520]

So I unplugged the egr and I also freshened up the cap, rotor and plug wires. Did the plugs last weekend. Drove like a new truck!  Did a fair stretch on the freeway then after well warmed it threw the SES on decel again.

To add to the fun the ecm fuse popped again rolling to a stop light. I am writing this as I wait to be dragged home for the 2nd time in as many weeks.

[VileZambonie]

Is it the ECM B fuse?

Check to see if the wiring to the oil pressure switch or the oil pressure switch itself is shorting to ground or the hot fuel handling module (if used) is shorted.

Check the wiring to the oil pressure switch, then disconnect it. If fuse B does not blow with the oil pressure switch disconnected and the wiring is OK, replace the oil pressure switch. If the fuse still blows, try disconnecting the hot fuel module. On R/V trucks, it is located at the base of the steering column.

[former520]

***Update and new problems***

So I tracked down the short to the 4 plug connector at the ecm.  The wire shielding had dried up and pull back about an inch from the connector. I am actually surprised that there where times it didn't short out!

I gave it the rest of the tune up with plugs, wires, cap rotor.  It was running strong and good. 

No smoking, currently the egr is unplugged at the harness. 

I had the truck off the road to do some bodywork and paint over tday weekend and put it back on the road today for a 180 mile each way trip up the mountain.  Running all morning climbing up it was strong and ran great.  Crossing the plateau at around 6500ft it started to buck and hesitate like it was running very rich.  I could floor it and it would clear out and run well.  It did this several times over the coarse of a few miles, then stopped and ran fine.  It was a 55 zone with gentle rolling grade elevations and it seemed to happen on the downhill only. 

On the trip back in oddly enough near the same area it did the same thing.  This time when I flooring it it surged then what sounded like a large explosion in the exhaust manifold on the drivers side.   Shortly after in another downhill section it died completely.  Due to the fact when it stall was a steep, curvy construction zone, I had my hand too full trying to keep it on the road and to a reasonable speed to give it a real try to restart it.  A couple miles later where the road opened up enough to pull off, I was able to start it by cranking it for not more than about 5-7 seconds and pumping the gas.  It drove the rest of the way home without any issue.

The codes it gave back where a 13 oxygen sensor and 24 VSS.  OXygen is a new one, VSS I was getting before, but I have since repaired the speedo cable and now have a working speedometer.

My gut is telling me to first try the fuel filter, new sensor and if it keeps up maybe the fuel pump.  Any other ideas or nuggets of wisdom from experience?

[former520]

Today I surged and died on the road going about 45mph on flat land.  I got towed into the office and I was able to get it started again by pumping the gas and cranking for a while.  When it finally started it was super rich, enough to water the eyes of all around.  No check engine light when it happened.  Anyone have any ideas?  I am running it another 400 miles across the mountain tomorrow.  Fuel filter is getting changed, I am going to bring a pump and hope to not have to change it on the side of the road.  Coil maybe?

[1980c10]

just for some thought;
-Coils tend to give more trouble on a warm engine. You can test the resistance across the leads to see if they are within spec; I am not sure what spec is but if you have a spare laying around you can check them against one another.
-It also wouldn't be a bad idea to test fuel pressure. due to the nature of your problem I would not throw a lot of parts at the dist as they are pretty cheap to replace the entire unit and you can pretty much rule out anything ignition related.
-You could also check the burn color on the spark plugs for consistancy if one is a lot different than you'll know where to look.

[Irish_Alley]

Test the coolant temp sensor it could be bad causing the ecm to give the engine more fuel than it needs.
The sensor screws into the intake manifold, on the front passenger side, by the thermostat housing.

Coolant sensor approximate resistance specifications:
177 ohms @ 212 deg. F. or 100 deg. C.
241 ohms @ 194 deg. F. or 90 deg. C.
332 ohms @ 176 deg. F. or 80 deg. C.
467 ohms @ 158 deg. F. or 70 deg. C.
667 ohms @ 140 deg. F. or 60 deg. C.
973 ohms @ 122 deg. F. or 50 deg. C.
1188 ohms @ 113 deg. F. or 45 deg. C.
1459 ohms @ 104 deg. F. or 40 deg. C.
1802 ohms @ 95 deg. F. or 35 deg. C.
2238 ohms @ 86 deg. F. or 30 deg. C.
2796 ohms @ 77 deg. F. or 25 deg. C.
3520 ohms @ 68 deg. F. or 20 deg. C.
4450 ohms @ 59 deg. F. or 15 deg. C.
5670 ohms @ 50 deg. F. or 10 deg. C.
7280 ohms @ 41 deg. F. or 5 deg. C.
9420 ohms @ 32 deg. F. or 0 deg. C.
12300 ohms @ 23 deg. F. or -5 deg. C.
16180 ohms @ 14 deg. F. or -10 deg. C.
21450 ohms @ 5 deg. F. or -15 deg. C.
28680 ohms @ -4 deg. F. or -20 deg. C.
52700 ohms @ -22 deg. F. or -30 deg. C.
100700 ohms @ -40 deg. F. or - 40 deg. C

[VileZambonie]

So I tracked down the short to the 4 plug connector at the ecm

What 4 plug connector at the ECM?

When it dies check for spark, injector pulse and fuel pressure