All,
I have a 1990 E-250 Mark Conversion Van with a 5.0 Liter Engine and a 4 speed automatic transmission. It has Dual Tanks.

Been trying to get this thing reliable enough so the wife can get the van on the road. Kind of need this van up in the next month or so as I am expecting twins in August and need the bigger vehicle. The vehicle has very low mileage (77K) original mileage. (Nope, it has not flipped 100K but the vehicle sat due to person having bad health - not able to walk etc. - long time Personal friend) Vehicle had set for almost 7 years.

Anyways here's the deal, I have replaced everything in the fuel system up to the engine with new parts. New meaning brand new not from a yard but from reputable dealer etc. This includes the fuel regulator, manual selector valve, pumps (internals and external), Ascending units, and even new tanks. Also all filters have been replaced twice. Originally the vehicle would not run. I have it to the point I can drive it to and from work but the issue is a performance problem.

Basically if I give much more then 3/4 pedal the engine just does not respond (it picks up likes it going to) and the RPM slowly drops down (way down) but does not stall. It might pop a little but never stalls. No Engine light is being displayed.

I also noticed that 4th gear does not appear to engaging or if it does it slips out. Supposedly the original owner had the trans rebuilt but no receipts to back it up and he is now passed away. Not sure if related or not and I can rebuild/replace the transmission. (handle it as a separate issue)

I am wondering if the TPS is bad.... or looking for what other thing could cause this performance problem?

I have already replaced the fuel regulator on the engine.

Also checked pressure ( Most recently after replacing Manual Selector Valve). Previously when the selector valve was bad, the engine would cut out do to the fuel pressure cutting out when I stomped on the pedal. (No fuel). Turned out that the selector valve was fill of gunk. I replaced all the filters and selector valve (new OEM).

Also it does not change performance (issue) regardless of tank selection.

That's why I question it being outside the fuel delivery system or being the external pump or after somehow but I am thinking something controlling it possibly. Maybe Ignition....I am kind of stumped.

Thanks,
Chris

 

Check the timing with a timing light and spout connector pulled. motor should be at 10* btdc, just make sure engine is up to full temp before checking.

Pulling codes both KOEO and KOER, the Haynes or Chiltons will have instructions as does this site if searched.

If the van also has a frame mounted fuel pump its possibly not supplying enough fuel. You should have 35-40psi at the fuel rail with Key on as well as when engine is running. I assume you have done a tune up with new plugs, wires cap and rotor?

Might even consider unbolting the exhaust y pipe from the manifolds and taking for a quick drive to rule out a clogged catalytic converter. Also check for vacuum leaks.

 

All,
Previously I checked the timing and was correct compared to Haynes manual (its been a while) but at the time it was correct. She was running warm at that time and I was trying to rule out things. I found out that the radiator was plugged and water pump was original so I yanked the hoses, radiator, water pump and thermostat and finally the fan clutch. Not to mention full flush. Engine temp is now good/perfect.

I will check the timing again (to be more recent) and also the exhaust by removing the O2 sensor.

I will also check the fuel pressure as its been a while since I have checked this and I have replaced the manual selector valve and filters since last test but at that time pressure read properly to the manual. Your numbers ring a bell. (Does not hurt to double check.)

I can tell you I had a buddy of mine (Manager at local Autozone) ran a scanner on the van. Said it was clean. I am not overly versed in the KOEO and KOER terminology, but I will look it up in the books I (Haynes/Chiltons/Factory Service Manual) for the vehicle.

Full tune up was done initially (plugs, cap, wires, and timing checked) and also a compression check (for prosperity).

In my adventures with this van I have also replaced the alternator,regulator, belts, and battery. The bearing had begun to seize in the alternator (loud/also was not keeping up with electrical demand (TV, stereo, lights etc.).

Also all brakes (front and back) and brake lines have been replaced as the original brakes had a blown wheel cylinder and lines had rusted out.

Also in the ignition system I have replaced the coil and ICM on the distributor. (This was me trying to figure out the Manual selector valve...dumb but engine was cutting out at that time.)

Also the muffler was rusted out and I replaced with I believe was a OEM fit muffler. No reducers, just cut the old off and clamped the system back together with two unions pipes.

To be honest I would have replaced all the "soft" parts regardless but its been a haul on this van considering I have like only 1000 miles on this van that's my own mileage.

Thanks,
Chris

 

Since you've already replaced all those other parts, a TPS is a cheap and easy replacement. You can test it with a voltmeter, an analog meter works best. Hook the positive lead of the meter to one of the terminals on the TPS; I usually stick through the rubber backing that the wires go through. The negative end of the meter is grounded. Then with the Key On, Engine Off (KOEO), slowly open the throttle, and watch the voltage vary. It should be smooth with no jumps.

A failed TPS usually results in stumbles in acceleration, or some steady state where you push the throttle to the same place all the time. It's used to tell the computer about sudden changes in throttle angle, so the computer can adjust fuel or spark accordingly to maintain drivability. If it's not working properly, the engine will stumble or backfire when you open the throttle, but an engine that's otherwise working properly will eventually get to where the throttle opening allows.

If your test of pushing the throttle to 3/4 open results in popping, can you vary the throttle slightly and get a smooth run? When one of mine failed, the engine would pop or stumble as I opened the throttle, but it will still rev. So I'm thinking something else is wrong with your engine.

 

All,
I am thinking it has to be the TPS or Front External Pump. I am leaning more towards the TPS as it does not stall out. It does have the popping as you describe but not always.

If it was a pump not maintaining pressure I would think it would stall out similar to what it did when the manual selector valve was full of gunk....basically previously it was starved for fuel and engine died.

I will get the TPS today...not sure when I will get it in the van though...got a fence going in this weekend and a pool next....going to have to fit it in after work...

Thanks,
Chris

 

All,
Got the TPS in place and I will tell you what it was the best 25 bucks I spent in a while.

The engine is now performing how I would expect a 5.0 Liter to respond, I even gave it a go on the local straight a way around here to see what she really could do and she did not miss a beat.

Anyways I am chasing two things yet and hopefully someone can chime in with procedures etc.

During the R&R (Remove and Replace) on this vehicle I replaced both the alternator, external regulator, and battery with new parts from Oreilley's.

The wife took her girlfriend, who is legally blind , and all ours and their kids to the doctors and it was a evening apt. last winter on the other side of town. Anyways I had to rescue them that night as the battery was dead. (I usually keep the battery on a float charger due to us using the vehicle so sparingly. So does anyone know the procedure to test the alternator/regulator is functioning properly as I have taken the vehicle out many times and personally have not been stranded and I believe the issue may have been related to someone leaving the door ajar and the battery running down while they were in the building waiting etc. The interior lighting system is decent in this vehicle.

Second and more of a major problem, I mentioned previously, is the transmission. The issue is 4 gear. It will shift in fourth as expected and appears to stay in fourth till I either let up on gas and it "free wheels" or I believe around 65-70 mph it may do it (free wheel) on its own. It appears to shift fine but does not maintain hold which if I am guessing may be either a valve body issue, the front band (burned out), or I am also thinking possibly a filter being clogged. The trans has no burnt smell and I almost positive I have not touched the transmission. I am fairly sure though I have the ATSG manual someone on this transmission....If any one would know this auto trans model it will save me some research/time. Also anyone have any pointers....I know shifting it as a 3 speed the transmission works as a decent 3 speed but with todays gas prices I would like 4th to be engaging.


Thanks for the help,
Chris