I'm in the process of resurrecting an '87 Isuzu Trooper. (Using the transmission of my old '86 that had been sitting for an embarassing number of years). Both have the 2.3L carbureted engines.

The '87 has been sitting for several years as well and will sputter if gas was poured down the carburetor before turning the switch.

I changed the fuel filter and put ~5 gallons of fresh gas in the tank (after draining most of the remainder out).

I've tried pouring gas down the fuel lines to fill them and prime the pump and even the float chamber, but still no luck.

It seems that the fuel pump needs to be replaced, but am I missing something?

Thanks for your help.

Martin

Double check the connections to the fuelpump under the truck by the gas tank. Small 2-wire plastic connector, tends to break. Also check fuses/relays that would pertain to the Fuel Pump. I recently replaced the fuelpump on my trooper to the tune of $110.00. Good luck.

- Jim

Luckily, you have a mechanical fuel pump, so you don't have to worry about the electrical connectors going to an in-tank pump.

The Haynes procedure for checking your mechanical pump is as follows (which some editorial comments on my part):

1.Check that there is adequate fuel in the fuel tank DUH

2. With the engine running, examine all fuel lines between the fuel tank and fuel pump for leaks, loose connections, kinks or flattening in the rubber hoses. Do this quickly, before the engine gets hot. Air leaks upstream of the fuel pump can seriously affect the pump's output.

3. Check the fuel pump diaphragm flange for leaks.

(at this point they should have said, shut off the engine! Also, at this point have an assistant standing by with a fire extinguisher, preferably not a smoking assistant

4. Disconnect the fuel line at the carburetor. Disconnect the ignition coil and ground it on the engine block (using a jumper to prevent sparks) so the engine can be cranked without it firing. Place a clean container such as a coffee can at the end of the detached fuel line and crank the engine for several seconds. There should be a strong spurt of gasoline from the line on every second revolution.

5. If little or no gasoline emerges from the line during engine cranking, then either the line is clogged or the fuel pump is not working properly. Disconnect the fuel line from the pump and blow air through it to be sure the line is clear. If the line is clear then the pump is suspect and needs to be replaced with a new one.

6. If the fuel pump flow capacity is adequate, check the fuel pressure by attacking a fule guage to the same fule line and cranking the engine. The fuel pressure should be approximately 3.5 psi.

Thanks for the replies. It is a mechanical fuel pump - unfortunately (I think).

I can't get the engine started (unless I pour a little gas down the throat of the carburetor).

I'm thinking there may be 2 problems, both the fuel pump and the carburetor, but I'm still not certain. For the fuel pump, I tried to prime it from the carburetor side, but it continues to flow back towards the tank - like the check valve isn't holding (at least I think that's how they work). I've tried to turn the engine over with the fuel line discharging into a container as Jim suggested, but no luck (I'm not certain if fuel reached the fuel pump from the tank since I drained it).

As for the carburetor - I was able to pour fuel into the float chamber - and can even see it in the glass, but I still can't get it to start on it's own. (After sitting for several years, I think the jets may have clogged).

If there is any magical advice - I'd greatly appreciate it.

Otherwise, I'll plan to replace the fuel pump and try to rebuild the carburetor from my '86 Trooper to put on the '87 (they seem to match).

Thanks for your help.

The pump shouldn't require priming, or everytime someone with that vintage or earlier of vehicle would have had to prime it whenever they ran out of gas.

I once had a VW Rabbit that displayed similar symptoms but it had the bad taste to do so on the freeway, 50 miles from home. I eventually was able to apply compressed air to the fuel line and blew years of accumulated junk back into the tank. The Rabbit then cheerfully ran me home. I then dealt with the junk in the tank in a user-friendly environment than the shoulder of the freeway.

Since your filter is near the rear, you would have to do the process in two steps, one from the filter aft and one from the filter forward. On the one forward, disconnect the in-coming fuel line from the pump and catch the junk in a suitable container.

I think Jim has the right idea. The pump does not require priming normally. I just put a new one last week on my 86 when I redid the head gasket and it just needed to crank over for a bit before it fired up.

You can pull the line loose right under the intake manifold, there is a doodad inline right before the pump that you can get to pretty easy to pull the incoming line off. Then pull the line off back at the fuel filter. Stuff the end of an air hose in one end or the other and shoot the crud out of it. Gas and gunk will likely come out of the other end, so you should try to capture that to be environmentally friendly. Then blow into line from the filter to the tank. You'll be blowing junk into the tank but there is the hope that once its loose it can then flow into the filter later instead of clogging you back up. It helps to pull the gas cap off when blowing into the tank as it will build pressure and splash gas back at you, especially on the side of the road when you are blowing air in with your mouth. (Don't ask me how I know)

If it isn't firing up with gas in the carb bowl then you are probably right to think the carb has some issue as well. It should run at idle for a good 30 seconds on a full carb of gas.

The only thing that made me happy about having to redo the head gasket on my 86 was that I could do the fuel pump out in the open. If you end up needing to replace that sucker it is a pain to get to it and get it free. I hope you can get it going without resorting to that. On mine the pump still worked, but it was blowing oil out the breather tube. You should have a rubber hose going down to the motor mount on that side, see if it is dripping oil or fuel out. That will tell you a lot about the condition of the pump itself.