Topic: 1987 22R Having Stuttering issues while driving or acceleration

[txf54]

Hello all.
I'm new to this site, and was wondering if you guys could help me figure out this damn problem rather than reading on and on about other people problems with their trucks 

What I have going on is my 87 pickup doing some odd thing while driving. It sat for over seven years before I bought it two months ago, doing a complete tune up to the truck. All new ignition parts, besides a coil, new fuel pump, carb rebuild and tune-up, and timing set to factory, more that I probably can't remember to name.

After my carb rebuild and tune-up, the truck starts up, runs great, idles perfect, but every now and then has a slight stutter when cruising, like 3-4th gear half throttle. It goes away often, but when it happens it gives me a headache, especially when I'm on uphills and such. It hasn't gotten crazy stutters, just slight. Sometimes when I left off in first gear to. Any ideas? Thanks!!!

[txf54 [OP]]

I should also add that when I first start the truck up before I leave anywhere, it will idle perfect for a few minutes and then shut off like I took the key out... No stutters before then, just shuts off. 

[Lewis Hein]

Mine did this once, especially after long pulls uphill at high RPM. It got to where it would give me FITS. Turned out to be the fuel filter. It's cheap so I would replace it if you haven't done so already. Also maybe the fuel tank is grungy inside and spitting bits of cloggy stuff into your fuel system? I suggest checking
 the inside of the tank as well.

[txf54 [OP]]

I replaced the fuel filter by the tank recently, but it didn't really seem to help the issue.

[txf54 [OP]]

Today, I also noticed that when I started it up this morning, it needed some serious pedal help to keep running, given it is 35-40 where I live in the cold mornings. Maybe fast idle out if tune?

Anyway, after it warmed up I went for a drive and it didn't do the stutters, the only thing I have done is put a full tank of 87; I usually run 89-91.

[txf54 [OP]]

Update.

Pulled off the carby and reset the bowl, and cleaned up a few things here and there. It drives fine, but still get a stutter after startup, warm or cold. Maybe a bad fuel pump? Just bought a new NAPA one but I've heard that the stock ones can't be beat.

[txf54 [OP]]

Update.

The truck severely needs my help on cold startup, but afterwards it runs great. Choke is working properly too.

[Lewis Hein]

Maybe an intermittent ignition problem? Ignitors do go bad on these trucks once in a while, although much more often they fail completely and with no warning at all

[txf54 [OP]]

Thanks, I'll look into that. So start by testing the pickup, coil, ignition module? I was told by my shop teacher that they can run great and then just out without warning, causing horrible misfire, and sometimes just shut off like the key was taken out.

[txf54 [OP]]

I also noticed that the fast idle cam will sometimes engage, depends on how it feels. I can always set it with my hand, and I will always disengage after warmup, but never seems to click in when I press the pedal in the morning.

I've also had to richen out my carb a few turns to run right. Maybe because of altitude?

[Lewis Hein]

I also noticed that the fast idle cam will sometimes engage, depends on how it feels. I can always set it with my hand, and I will always disengage after warmup, but never seems to click in when I press the pedal in the morning.

The fast idle cam issue sounds like the heated spring thingy that actuates the choke may be weak or out of adjustment. My choke closed pretty lethargically and I had the same fast idle issue before I tightened it up. I know you said the choke is adjusted right so you probably know all about that.. However in case it's helpful:

There will be a little black housing under the air cleaner unit on the firewall side of the carb, with a wire heading off to the harness. Inside this housing is a bimetallic clock spring and a heater. When spring is cold it twists the choke plate closed and, via a linkage, engages the fast idle cam. If you shut the truck off when hot, the steps on the fast idle cam will prevent the choke from closing or the fast idle cam from engaging untill you pump the accelerator pedal. The heater comes on at engine startup and slowly heats the clock spring so it slowly opens the choke. I believe on some earlier R series engines this heating was accomplished with coolant flow through and not electricity.

By twisting the housing you can adjust the tension in the clock spring when cold. If you twist it too far the choke will never fully open, even when warm. This unit is usually held in with rivets, which you will have to remove and replace when done. You can then twist the plastic housing to put more tension on the little rod that the choke plate is attached to.I would suggest replacing the rivets with machine screws if you think you will fiddle with it much.

[Lewis Hein]

 

Update.

Pulled off the carby and reset the bowl, and cleaned up a few things here and there. It drives fine, but still get a stutter after startup, warm or cold. Maybe a bad fuel pump? Just bought a new NAPA one but I've heard that the stock ones can't be beat.

I agree, parts store fuel pumps get a deserved bad rap. The OEM Kyosan pump will cost less in the long run and strand you less

[Lewis Hein]

One final suggestion. It helped me immensely when fiddling with my carb to have another one on hand. I could take it apart, fiddle with linkages, and figure out what moved what without craning my neck around and trying to see around corners with it still on the truck.

[txf54 [OP]]

Thank you for all the suggestions! After all I ended up pulling off the carb one last time and cleaning and adjusted the fast idle Cam and all the springs and linkages. Now it seems too fast idle very well, but it still isn't idling as high as it should be. The factory service manual says it should be at 3,000 RPM, but even when cold I feel like that's way too high. So for now, I'm fine with just where it's at. Seems to be running great to, no stuttering, stalls, and now I'm getting about 16 to 17 MPG and I live in the hills 

Every now and then it'll still shut off like I took the key out though. So I think I'm going to start testing the igniter, ignition coil, pick up coil, etc. Any suggestions on that?

[txf54 [OP]]

Update:

As of now, I had figured out another problem I was having. Starts in the cold morning seemed as usual with the stock carb. Pump, runs, dies, pump again runs. But that little piece of heater ducting from the exhaust manifold to the air cleaner box was damaged. I replaced mine and clamped it down with hose clamps, and now my fast idle works even better in the morning? I doubt this will fix most other cold start problems, but it definitely fixed mine. Now it runs good on cold mornings, despite my exhaust leak off the manifold. Gonna have to replace that soon enough