I've got an 87 S-15 with a 2.8 and throttle body fuel injection. One of the injectors is making a very audible rapid clicking. What does this indicate? It also sounds like a vacuum leak whistle coming from the top of the throttle body. I don't have much experience with these type of fuel delivery systems so any help would be appreciated.

Looks like we'll be doing a clutch soon too, they sure don't leave much room to get to the top bellhousing bolts...

Thanks.

 

How is the truck running? Injectors have a certain amount of noise associated with their operation.

The whistle... Is it only audible with the air cleaner off or can you hear it with the air cleaner on? A whistle with it off sounds like normal operation. At idle, the throttle body is allowing such a small amount of air into the engine that many times it sounds like a vac leak.

To gain more room to get those top bolts, remove the transmission cross member and drop the back of the trans down lower. This should gain you enough room to pull the top bolts. You may still need a bunch of extensions to get your rachet (air wrench or whatever) to a spot where you can use it, but it'll be much easier than attempting to do it with the trans at it's normal installed position. IIRC from when I pulled the auto tranny out of my old '85 S10, I had to use a swivel extension to get to the top two bolts even with the trans down, but that was a long time ago.

Good luck and keep us posted!

 

Great idea to drop the tranny down a bit in back.

The clicking sounds like a really noisy lifter. It's loud with the aircleaner on but much louder with it off. It's coming from the rear injector. The whistle is louder with the air cleaner open but can be heard well with it closed.

Thanks.

 

I'd probably start by running some injector cleaner through the tank and possibly pull the throttle body off and clean everything up. After that, possibly use an unlit propane torch (soldering torch) to probe around the base of the TB as well as any vacuum ports and the throttle shaft to see if the idle increases. Do this with the air cleaner on so the propane won't get sucked down through the TB. The propane test should let you know if you have an external vac leak.

Like I said, a whistle very well could be just normal unless it is something that just wasn't there before. If you decide to pull the TB, check everything to make sure that it is tight and replace all of the gaskets (they're cheap enough).

On the clicking issue, I would take and start the motor. Now with a screw driver (or a mechanics stethescope) put the tip of the screwdriver on each injector and your ear to the handle end of the screw driver. Compare the sounds from each injector.

Next, visually compare the spray patterns of the injectors. They should look about the same. If not, you may need to replace them. I have never had good luck replacing just one injector on a dual injector setup as they both wear during their lifetime and one new injector may not flow the same or even close to an old worn injector given the same pressure and pulse width.

 

Great ideas to check.

I watched a mechanic use propane from a 5gal tank (he told me I didn't see it...) on a Honda of my wife's that wouldn't pass smog due to a vacuum leak. He nailed it and it was fixed in minutes. I hadn't thought of using my small torch. My son is driving the truck but after l heard the sounds from the bellhousing last night it'll be drydocked when he gets home tonight. Actually the clutch is still engaging well- I'm guessing we're having bearing issues, a bad finger on the pressure plate or maybe even a disc spring out of place. I hate dropping trannies....I hope his girlfriend isn't going to miss him for a couple days because he's going to be busy....

 

I hear ya on the droppin' trannies part. I replaced a clutch/pressure plate in a friend of the families F150 awhile back. I really wish that truck was a manual linkage clutch. It was hydraulic... I didn't want to break the hydraulic line loose and have to bleed it back out, but that left me with holding the trans up in the truck while changing out the clutch. Didn't leave much room for working between the engine and trans. Plus the pressure plate was a heavy pig and can only be put on ONE way. Man was that fun. Not to mention how long it took for the hydraulic throw-out to self adjust to the new clutch position. It didn't disengage right for a week worth of the guy driving it, but gradually got better.

Good luck with it!