Cabby Not With The Program

[Little Betty]

I have a 1987 Cabby. I have done the following to it:

Removed the AC
Deleted the cruise control
Changed the intake manifold to a Fox
Relocated the cold start valve
Installed a Neuspeed Throttle Body
Installed a four light relayed headlight system

I am having a the following problem.....

The car runs like a champ until it gets warm, then it staggers, and eventually won't hold an idle, and will quit dead. If you wait long enough (and it's not long... maybe 5 minutes), it will restart , but as soon as you get it warm (especially at stop lights etc.) it will quit.

I have done the following:

Changed BOTH the fuel boost pump and the in-tank pump.
New water pump and thermostat.
Checked the rad, and it seems to flow water out as fast as you can get it in.
Changed the fuel distributor - no change - so changed it back
Changed many of the vacuum lines and all the plug wires, and the coil
New fuel filter - made no difference.
Changed the rad fan thermo switch - no diff, so changed it back
Rad fan rarely runs, but seems to intermittently when it gets hot (no after run...hmmmm)
Changed the WUR, no difference
Get fuel pressure to the filter, have fuel pressure to the fuel dizzy
Gas tank seems to pressurize BIG TIME when it is running
Fuel pump relay seems ok, doesn't run hot. Jumpered the relay, and the pump runs
When the car quits the pump makes a real strained sound before it shuts off.

I am out of ideas, OUT of ideas. Anyone have a suggestion? I would like to drive this car before the summer is over.

[Briano1234]

Bingo
When the car quits the pump makes a real strained sound before it shuts off.

Sounds as if you have a primary/in-tank pump failure.

[kamzcab86]

Why was the cold start valve relocated, and where was it relocated to? (Just curious).

My educated guess is that either the fuel pump(s) is/are overheating, or:

The car runs like a champ until it gets warm, then it staggers, and eventually won't hold an idle, and will quit dead. If you wait long enough (and it's not long... maybe 5 minutes), it will restart , but as soon as you get it warm (especially at stop lights etc.) it will quit....
Gas tank seems to pressurize BIG TIME when it is running

It's quite possible that the fuel tank is not venting properly, which indicates a fault in the evaporative emissions system.

[Bugly]

I replaced short hose on in-tank pump after replacing both pumps, filter, etc. and had same problem you are having and it cured the problem. The hose looked ok but......

[Little Betty]

Thanks for your review and input. I have changed the in-tank pump, and the short piece of hose for a new piece of fuel hose. No difference.

I have changed the high pressure fuel pump, no difference

I drove it around (well.... staggered around) without the gas cap off to see if the tank vent system was bogus, and it made no difference.

[Little Betty]

With respect to the cold start valve, I installed a Fox intake manifold under the impression that if flows more air. I have since learned from an excellent article on the web, that this is probably not the case.... but I had already installed it by then.

The cold start valve on the Fox is located adjacent to the throttle body facing the rain tray. The problem is that there isn't sufficient room between the rain tray and the valve, and you run the risk of snapping that valve off is your engine mounts allow any front to back rotation of the engine. So... I sanded a flat spot and drilled a hole in the manifold where the cold start valve normally appears in a cabby, and installed the valve there, blocking off the original location with an aluminum block off plate I fabricated.

[Little Betty]

I am going to yank the in-tank pump again! (grrrr - it is the worlds most dangerous job) and check that hose again and replace the pump, again. Maybe I screwed this up some how. I am, after all, not a mechanic.

I will report the results.

[Calimus]

I recently delt with this with my wifes 87' rocco. I also had replaced the in tank pump with a NOS one from the dealership. Well, the pump powered up, made all the right noise so I installed it. Problem kept on. Replaced the main pump, problem continued. Spent months replacing this/that and the other, main pump would whine when the car got hit from sitting still and would die.

Just out of pure frustraition, I pulled the hose to the in tank pump and hit the key. Low an behold, pump made noise but didn't pump a single drop of fuel. Replaced the pump again (you can bet I made sure it pumped fuel this time) and I have now been driving the car for 3 weeks without a single failure. Check and make sure your in-tank pump is actually pumping fuel. If not, that will put a strain on the main pump causing it to overheat when at idle and shut off.

Good Luck

[gull]

If it doesn't turn out to be the in-tank pump, I would check the O2 sensor. But it sure sounds like the in-tank pump to me. Those are exactly the symptoms I had on mine when the pump was going.

[Little Betty]

It was the in tank pump. What confused me was I had TWO bad in-tank pumps, so I was having problems understanding the problem. I finaly installed my third pump and it worked a treat - well... sort of. The tank vent system was also faulty. When I bought the car it had completely shot struts on some sort of 60/40 cup kit. It was very bouncy. I drove it to the gas station one day and hit a MAJOR bump that had all four wheels off the ground (just not at the same time). I believe this disturbed and jammed that vent valve in the passenger rear wheeel well. I took it out and it reset itself, and now the tank vent system seems to be working fine as well.

[Bugly]

You might want to check vent hose above wheel well. if tire rubbed a hole thru it, it will make one heck of a mess in the tank.

[gull]

Note to self: Check the fuel tank vent valve if I ever jump my Cabby.

[sixsracing]

I jump mine all the time, guess I'll be needing to check that also.