dbsoundman

Hi guys, I have a pretty beat up 1992 F150 2wd with the 4.9 motor and a retrofitted Borg Warner T18 manual transmission. When I bought the truck I knew it definitely had some issues: the radiator was basically clogged with rust, so I replaced the whole radiator first thing. The water pump now leaks and that's on the docket to do next. The body is rusty, and it's generally just not pretty, but it ran and drove fine since I bought it in June. I don't drive it daily; maybe once a week or so.

Last time I drove it was two weeks ago and it was just fine, but today I went to drive it and noticed that it didn't seem to want to hold idle; it would randomly almost die, then come back. It did NOT surge, just dropped idle RPM (don't have a tach but I could tell by the sound/feel). It didn't happen terribly often when not in gear, but I did notice if I had it in gear and let off the gas it would sort of lurch because the engine would just drop RPM rapidly, like I dropped the clutch or something, but I was just coasting in gear normally. If I'm giving it gas it runs all right. I also noticed a really heavy smell of unburnt gasoline. (The exhaust manifold is pretty leaky so the truck was already smelly but this was a distinct change.)

As far as I know, basically everything on this truck is more or less original or at least old, I have basically no maintenance records. I know the fuel tank and pump were replaced (only the front one, the rear one was removed), but that's about it. I'm not really interested in investing a ton of money into this truck as it's kind of a lost cause from a restoration/rejuvenation perspective, but I was hoping to keep it running for a couple years at least. Are there any basic items I can check and/or replace that are not too expensive? Otherwise I'll probably be putting it on Craigslist for the same $500 I bought it for...

Thanks!

-Dan

Thoroughbred

>"heavy smell of unburnt gasoline"

>"fuel tank and pump were replaced"

holy **** $500

>"it would sort of lurch ... I was just coasting in gear normally ... if i'm giving it gas it runs alright"

ok it sounds like i had this exact issue = sputtering when cruising but mashing gas made it go. The solution ended up being a fuel pump with lower-than-recommended psi output.

so when you say fuel pump was replaced, and smell gasoline, it makes me wonder if either the line is leaking or the pump is below standard/faulty.

i would never have known, but i asked a mechanic to check the psi in the fuel line (he charged me $20). that test showed that the pump was pushing out around 35 psi. apparently the recommended pump for mine (96 I6 manual 5speed) should push at 90 psi. slight disparity = of course it was sputtering

so it had an inferior pump. the plot thickens - it also had been replaced recently. here's the thing: the mechanic who replaced it said that the packaging/order listing made no distinction between the 90psi and the 50psi versions of the same pump. in other words, i think he probably looked up the part, saw two identical pumps, and naturally chose the cheaper one. because he's a master mechanic ... who accepts nothing less than the very best

and they couldn't tell the difference when they drove it (because let's be honest why do some salty ******* mechanics care about performance issues on my old truck?), but I could tell the difference between the front and back pumps, and how the truck responded when i pressed the gas.

so that fixed my issue, if i was in your seat i'd ask a mechanic to check the fuel line psi. at least it might rule out that possibility.

dbsoundman

Wow, that's really interesting... something to look into! I'm actually wondering if my fuel lines are just leaky, but either way I'll look into the fuel pressure after I try the obvious stuff (inspect/clean the IAC and MAF, stuff like that).