Geek in search of mechanical input
 

1990, Isuzu, 5 speed, 2.6 liter liight truck.

Has no power all of a sudden. Starts good and will hold speed on a level road but hills are a nightmare.

Local repair shop says I need a whole new fuel pump system ($700+). Searching the web has brought the info that it may be just the fuel pressure regulator ($50 + install).

Any quality input is VERY welcome.

2Wolves

I don't know much about fuel injected cars, but your injectors could be fouled, the fuel pump could be shot, there's a lot of things that could happen.

Did it just all of a sudden drop in horsepower? Have you checked your spark plugs? A lot of the time one or two plugs can get so dirty it'll stop firing that cylinder.

Also, is the mechanic saying you need a new "fuel pump system" or a new "fuel system" cause a fuel pump is cheap as hell, a fuel system isn't. Ask them specifically what's wrong, make sure you don't get ripped off.

Yeah be sure to get the Specific problem, not"its in the fel system". If you want, before you commit, put in new plugs, and buy some of that injector cleaner that goes in the tank.

New plugs, new rotor, new distributor, new plugs.

New manifold gasket.

Yes, I tried the pour in the tank injector cleaner, twice.

Guy is saying "New Fuel Pump Assembly" hence the high cost.

Or should I just shoot old 'Faithful'?

2Wolves

Go for a regulator, if that doesn't fix it, try a fuel pump. Shop around for prices though, as $700 sounds high. Check a Haynes/Chilton's manual to see how difficult the job is. You might find that you can do it yourself.

Oh, and try a new fuel filter before you do anything. Ya never know.

well my fuel gauge doesnt work and ive talked to people about it and i would have to have the fuel pump assembly replaced to fix it... the hardware is like $200 but its pretty labor intensive... they have to pull out the fuel tank and whatnot... so the labor raises the price to like $500+ in my case... maybe something along those lines in your case as well...

One thing to check out is if it is an in tank pump or an inline pump. I just had to replace an intank pump in my mustang which is a pain. You have to drain the tank and drop it out of the car. If you have some idea what you are doing it is worth it becaue of the money it saves, but if you have little or no car expirence it probably isn't a good first project. However, if you have an inline pump that might be something that you could do fairly easily with the aid of some sort of shop manual or something.

Is your fuel pumped controlled by a relay? If so, the relay may be going south on you. Relays are usually much cheaper than new fuel pumps.

Just an idea.

Get a fuel pressure reading to verify you have a fuel pressure problem.

These engines are notorious for vaccuum hose leaks. Take a can of carb cleaner and spray it around all the vac hoses, if you get a different idle, you may have a vac leak.

Also, check out 4x4wire.com in the isuzu sections, there are some helpful people in that forum that know everything about these engines.

Thank you.

2Wolves

I suspect the mechanic who wants to replace the entire fuel system for $700 is trying to rip you off. Try another place and see what they say.

It sounds like fuel starvation or weak mixture.

Fuel pump problems sounds plausible - fuel aint gettin to the combustion chambers in sufficient quantities to give full power.

Then again (& without knowing exactly which or even whose FI system is fitted to your truck) fuel pumps are usually grossly over engineered and either work or don't.

So... Looking elsewhere...:

Too little fuel is the same as too much air. Do you have a perished vacuum hose or cracked manifold or fittings?

Check plug connectors around the various sensors, particularly around the air filter.It's very possible that the fuel metering is being "misinformed" due to a corroded electrical conector.

MOST IMPORTANT! Get the car to an auto electrician or fuel injection specialist. Too many garages today will simply fit new components mindlessly until a problem is solved.

Mike.

a quick check of Partsamerica.com (the online shopping arm of Advance Auto) reveals that, in my zip code, there are half a dozen AA stores that have your pump in stock, priced at under $100 and carrying a lifetime warranty.

IF you can verify that the pump is indeed in need of replacement, then your best bet is to buy the part yourself and then find a mechanic to do the job for you (if you cannot do it yourself). Although replacing an in-tank pump (which yours most likely is) is not extremely difficult, it does require a certain amount of mechanical ability.

2Wolves,
Your truck requires 37 psi at an idle and 46psi unregulated, which means with the vacuum hose off the regulator.

The fuel pump can still deliver that pressure but can not handle the volume required for a load.
Which means driving at a steady speed your truck will run fine but under a load(up-hill or heavy accel) it has a hard time moving.

Your in -tank pump requires 2.5 hours of remove and reinstall time.
Make sure they replace your in-line filter because it will have all the metal from your fragmented pump.

If you have any other questions feel free to pm me.