So a vacuum leak at the throttle body could be causing these problems? Thanks for mentioning the helicoil, I was thinking something like that must exist but I had never heard of it before. Could you tell me a bit more about it; and is it possible to procure just what I need to fix this one bolt hole? The info I've been able to find online has been a bit confusing, and expensive looking.

 

Should not be a problem to buy the helicoil kit for just you size bolt. Any decent autoparts store should be able to sell you the size you need.

 

That's good to know, thanks for the info. Me and my bolt'll be taking a trip to the parts house.

 

The power loss problem came back today. The truck had been running ok but today while I was on the freeway going about 70 my truck began slowing down. I was able to go around 45-55 mph, but the engine was really dragging. It kinda feels like I'm suddenly towing a heavy weight or something. When I stopped I checked the fuel pumps and both were audibly running. I am really stumped on this problem and I need to figure it out.

To date I've done all the work listed in previous posts plus checked the fuel pressure regulator for fuel in it's line. It was replaced a few years ago and still seems to be fine. I have relatively new pumps, injectors, plugs & wires, fuel filter, fuel relay, distributor cap and rotor. Anyone know anything else I can check? I wanted to check fuel pressure, but since the truck runs fine most of the time I'm sure it's fine, and I can't locate the valve on the fuel rail anyhow. Any ideas?

 

How old is the fuel filter??

 

The fuel filter is about two weeks old. I forgot to mention that the engine will suddenly pick up and run at full power but then cut out again.

 

Grab the main engine wiring harness along the firewall and gently move it to and fro and up and down to see if it causes the engine idle speed to change at all. My daughter's did something similar to this and it was a chaffed wire that was a real bugger to find. While hers is a 97, you could have a similar problem.

 

I'll be sure and try that. Speaking of irregular idle... When I start my truck the idle will start out smooth then get rough, in fact with the hood up you can see the engine shake a bit, then go real smooth for a few seconds then get rough again, repeat. I've assumed it to be because my timing is off, but I always wondered why it would smooth out for a few seconds before getting rough again. I guess my old truck has her share of problems.

 

The problem with an older truck likee yours (and my daughter's for taht matter) is that most folks are not as concerned with keeping it running well as you are. Consequently, there is not the level of expertise out there to troubleshoot these problems that you would hope for. I had a 93 F150 with a pinging problem that I spent two months chasing last summer. I took it places to get it looked at and nobody could ever find it. Turned out to be real simple. An arcing spark plug wire. It was arcing out on the valve cover. Re routed the wire and the problem was gone. Chances are good that you have a simple problem somewhere. Keep at it, you will find it.

 

I agree it can be very frustrating figuring out what is wrong with these old vehicles sometimes. I really appreciate all the help and ideas you all have given me. I'm gonna go out and mess with it some more, particularly I'm gonna go jiggle the wiring harness like you suggested. Maybe someday I will be able to afford to retire this old truck, but I've gotta keep her running for a few more years. On the bright side it ran perfect again last night.

 

The intermittent problems are the worst. It's wither something loose or something that gets hot.

You can do with this piece of information as you wish as it comes from experiences with boats. Most of my intrmittent boat problems have been electircal. One was a difficult to locate dirty ground that took me two months to find. The other was a starter problem. Most of the time it strted just fine but occasionally nothing would happen when I went to start the boat. It turned out to be a flat slide on coonection to the starter. The terminal on the starter was fine. The wire however was a different story. The wire had the female connection. Over twleve years or so, it had become corrosed inside of its protective cover. Becasue it had corroded, it had gotten hot when starting the boat because of the dirty connection. The heat casued the female connector to loose some of the spring tension that causes it to stay connected to the male flat connection on the starter solenoid. Now it was loose and dirty. NEw wire and connector fixed it but it had been a big problem since middle of last year. I did not figure it out until about six weeks ago. Boast shop's solution was to replace a perfectly good $125.00 starter.

I really think you have a minor problem somewhere and it may be a bad connection of chaffed wire. Could also be a small vacuum leak. Good luck.

 

I tried shaking the wire harness and nothing happened so I guess that's ok. The truck has ran fine since Thursday, I'll just have to keep an eye on it I guess.

As for that hissing sound I was hearing, it is coming from a tube that runs from the brake booster to a vacuum connector on the upper intake manifold. The tube ends in a rubber stopper like piece that goes into the booster and that is the spot where the hissing noise is coming from. If I touch the piece it will hiss. Is this normal?

 

I would not think this is normal. Try to get it sealed so the hissing stops. Hopefully this requires nthig more than a new hose or cutting the end off of the existing one and puttin it back on. I suspect this is a vacuum leak which can impact engine perfomance in all sorts of ways.

Does it hiss if you don't touch it? If no, this could be the intermitant problem. In any case, it should probably be fixed anyway.

 

The offending noise is coming from the little rubber plug in the front of the brake booster. It's a round piece of rubber which connects to a large rubber tube that runs to the vacuum T on top of the upper intake. I first noticed the sound about a month ago; I've been driving this truck for about five years. After driving, when I cut off the engine it makes a loud hissing sound for about 10 seconds or so. I noticed the other day that if I pushed a bit on this round rubber piece that I could make it hiss again. Would I be able to get a replacement part like this? Should I try sealing around it with some RTV or something?

 

My suggestion would be to make a run to O'Reilly's this evening and show someone there what you have. They will be able to tell you if the can help or if the dealer will be able to assist. I am just not familiar with the brake booster and vacuum system on your truck. That said, if you have a vacuum leak, especially if it is significant, it will affect engine performance. If the hissing comes and goes, it could be the intermittent problem you have ben experiencing. May not be, but if it's a vacuum leak, you really should get it fixed. Vehicles of that vintage had quite a few vacuum operated controls. If you ahve a vacuum leak it can cause any number of things to not operate properly. Wish I could provide more definitive answers but like I've said before, I just a weekend hack who hates to pay to have things fixed.