Steven Posted October 9, 2020 Share Posted October 9, 2020 I drove my jeep everywhere, decided to head to the beach. At a half tank or less it runs fine, but when I filled it up the jeep bucks, skips and runs rough in first and second gear. I thought it may need a new fuel pump and filter. Replaced both. The same thing, under 3/4 tank of gas runs fine. Fill it up and runs rough. Changed the plugs, still the same issue. Any ideas? Quote Link to comment Share on other sites More sharing options...
Administrators Moses Ludel Posted October 9, 2020 Administrators Share Posted October 9, 2020 Steven, try checking the the emissions EVAP system from the fuel tank and roll-over valves to the filler neck venting. Also check the EVAP filter and vacuum hoses in the engine bay. This sounds like the fuel tank is not venting properly, which could be as simple as the need for a new/correct fuel filler cap. I would start with a fuel cap change. The cap may be defective. If this does not do it, check the fuel pressure and volume of fuel flow at the TBI test port when the tank is full. Troubleshooting can proceed from there. Moses Quote Link to comment Share on other sites More sharing options...
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