I had a used motor installed two years ago. I use this truck very sparingly. I have, however, begun working it pretty hard, lately. I took the utility body off to lighten it and attached a two-car trailer. It really handled the job well!

It's automatic and the new motor sounds real strong when pulling up-hill. The tranny shifts smoothly and I was pleased. Several things bothered me, though: When I start the truck it belches black water out the tailpipe. It has had some fusible link failures due to burned wires on the EFI touching the manifold.

It also makes a high-pitched "swishing" exhaust sound when it's under load. I hear an intermittent "tinny" sound sometimes, like an exhaust baffle is flapping around. It's old, with high mileage, and I am putting it thru some vigorous exercise.

Yesterday I noticed the ammeter showing 10 amps charge. I also had the feeling that I was smelling exhaust fumes during the day. I cut short my day and was trying to make it home along the expressway at 70 mph before the battery died. I usually run it at about 60 mph but it seemed to take itself up to 70 mph comfortably.

When I got off the x-way (after 20 miles) it was running rough (something it hadn't done at all, before) and I thought the battery might be low and that affected the engine performance. When I opened the hood I saw that the hoses on the EFI had melted! What in the world is this all about?

 

Probably a clogged exhaust system or broken cat.

A charging problem... it should be 13.5-14 volts with the engine running. Use a multimeter to verify, if it really is 10v change the alternator.


What hoses... there are lots of them.

 

Thanx for the reply, and excuse me if I'm really dumb about these engines but the top of the motor has a couple plastic valve bodies with heater-hose-looking hoses jumping from the intake manifold to the exhaust manifold and other places. I don't mean the big three-inch hoses (I can tell that they are for the air-cleaner) or the small vacuum hoses like the one going to the power brake booster.

The hoses I'm referring to are about one-inch in diameter like a heater hose. The sit atop the engine next to the EFI. The one large valve body has melted and the attached hoses disintegrated. It looks as if it got really hot under there like there was back-pressure from a blocked exhaust. I took it to a garage I use and the guy says he's going to "cut-out" the cat-converter and put in a new muffler and pipes.

Any advice on how to improve the exhuast evacuation on this truck?

PS: The engine temperature didn't get hot (so I doubt if I damaged the motor) but with all the vacuum leaks it was running rough. It started-up today and I drove it over to the garage.

 

We really need a picture to figure out what melted on you, over the years they mounted things in different places and it's very ard to even guess what you have just from the description. Most of the vacuum lines are small little things, about 1/8" diameter, and if any of these are melted you will have drivability issues. The larger hoses may be part of the air injection system, the portions attached to the exhaust or heads should be metal to prevent them from melting. If one of these rusted out then you could possibly get hot exhaust comming out where it's not supposed to and melt other plastic bits.