97 Jimmy - new fuel pump/sending unit - engine bogging issues

[Novice Motorhead]

We replaced the fuel pump and tank. Rechecked all the lines. Poured in about 3 gallons of gas and the engine started on the first try. I took it for a short ride of about 3 miles. When I came to a stop, the engine died. So many lights came flashed on the cluster I can’t recall all of them. Restarted the engine and drove about 30 feet and it died. Finally got it restarted on a 3rd attempt and while driving it back to the barn, it died when turning into the drive way. I got it restarted and drove it about 100 feet and it was idling very rough. Tach was fluctuating between 200 rpm’s and 1,500 until the engine finally just died. It took me 10 minutes and several attempts at restarting it just go get it to back up and pull it into the barn to look at it again.

Today we will check the fuel pressure and replace the fuel filter. The Jimmy has just over 150k on it so I am sure it time for a new filter. I think we will check the wiring to pump. The new pump came with a new connector and we did install that. Also, gas gauge is either reading empty or ½ tank.

Thanks in advance for any and all suggestions.

[Novice Motorhead]

We couldn’t get the pressure as we didn’t have a gauge that was made for this era of car. Yes the gauge was that old. Started the Jimmy and it ran fine for about 10 minutes. We let it idle, put in gear, the rpm’s were around 200 – 600 and the engine sounded fine. We let it rest for about 20 mins and did the same thing with the same results. I drove it down the road and it began to hesitate again, only slightly. I put in about ¼ of tank of gas and it started right up so I headed home. About 2 miles into the ride I felt it hesitate or surge again. Less than a mile later is was surging more frequently. I pulled it over, turned it around and headed back to the barn. On the way back it died at a light. The rpm’s were anywhere from 0 to 2k. At the next light I put it in neutral, kept one foot on the brake and one of the gas, then slipped it into drive on the green and headed down the road. The engine surged and it felt like I was on a bucking bronco and I almost caught a cold from the movement of the needle on the tach. Today it sits in the barn with a For Sale sign waiting to be put on it unless I can figure this out. Any ideas?

[Tech II]

Can pick up a cheap pressure gage....all it needs is a fitting for the schraeder valve....Sears or any autoparts store has them....

RPM's are 200-1500? No wonder it's stalling.....rpm's shouldn't go below 550-600....

Rule of thumb....when a fuel pump is replaced, the sock inside the tank is replaced and the fuel filter is also replaced.....

Pressure should be above 60psi.....cycle key several times(don't start), with 10 seconds between cycles, to read max pressure....then watch gage.....it should not drop immediately.....in 5 minutes, 2-3 psi acceptable...

Other possibility, is there is not enough fuel in there....could be sloshing around and sucking air at times....

[Novice Motorhead]

I have owned this Jimmy for about 5 years and the rpm's have always been around 200 - 500 the entire time. We did try to increase them to the 600 range only to have them fall back down to the 200s within about 10 minutes of driving. I will pick up the fuel pressure gauge and go from there. Thanks

[Tech II]

No way that engine runs with the rpm's around 200.....idle is 600....

[Novice Motorhead]

I understand what you saying but when the needle hovers between 0 and the 500 mark (the thick line between 0 and 1), I call that 200, maybe a bit higher.

[Novice Motorhead]

Tech II - I appreciate your advice. Finally got the time to get back to working on the Jimmy. We replaced the fuel filter. Jimmy started just fine but 5 mins later all the issues returned. I was able to check the fuel pressure. 24 psi, exactly what you said was likely the problem. I cleaned the EGR valve but still have the same problem. I checked the voltage at the fuel pump with a multimeter. 10 to 11.9 on the meter. Resistance was 1 ohm. I think those are the numbers I want. I believe the problem is a blockage in the the fuel line. I am looking for a 90 degree Shrader valve anti-air loss adapter. My understanding is that I can screw this adapter on to the shrader valve and then attach the air hose to the other end and blow out the lines.

[old_master]

At 24psi the engine will not run, guaranteed. The poppet valves require a minimum of ~43psi before they will open and squirt fuel. Recheck fuel pressure and leakdown using this procedure: Key ON, engine OFF, fuel pump running, fuel pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes. Post your results.

[Novice Motorhead]

When we initially checked the pressure we used that method. We did it again using said method with the same results. 24 psi. Because the fuel pump is in the tank, today I will disconnect the line between the fuel filter and the engine and roll the key to the on position. I will attach a hose so I can monitor the flow and check to make sure the pump is working and for a blockage between the filter and the tank. If that is clear, then I will disconnect the fuel line at the engine and blow compressed air down the line back toward the filter. I will attach a coffee filter loosely over the end of the line to catch any sediment that hopefully dislodges.

[old_master]

Disconnect the fuel line at the filter and check pressure there. You'll need to modify the pressure tester so all fuel flow & pressure dead ends at the tester. Pressure must be 73psi to 108psi and remain above 55psi for at least 10 minutes after the pump shuts off.

[Rick Norwood]

Can I ask what brand name of fuel pump you installed?

[Novice Motorhead]

Once I got under the hood and looked at what little space there is to work on the fuel line, I decided I would take the Jimmy to a local shop. Not much fun driving a vehicle that is not getting the required amount of fuel. Shop was about 7 miles away and the engine died 5 times on the trip. I took the side roads at about 7:00 a.m. in the hopes of avoiding traffic. They looked it over and told me it was a bad fuel pump. I had them replace the fuel pump. Runs much better now. Thanks for all the advice.

[Rick Norwood]

Originally Posted by Novice Motorhead

Shop was about 7 miles away and the engine died 5 times on the trip. They looked it over and told me it was a bad fuel pump. I had them replace the fuel pump. Runs much better now. Thanks for all the advice.

How much you wanna bet the "NEW" Fuel Pump that was bad and had to be replaced was an Airtex Piece O SH*T Fuel Pump?