My 2000 GMC Jimmy will not start when it is raining or is damp outside. I have a new fuel pump, new battery and the starter is fine. The engine will turn over but will not start (unless it is sunny out). Please help? Would it be a bad distributor cap? or maybe bad wires? Can I solve and fix the problem myself or do I need to take it to the shop where they will charge me LOTS! Thanks, Jennifer

Did you take the distributor cap off and see if it has moisture inside ?

Can you jumper the fuel pump and make it start and continue to run ?
Have you checked to see if you are getting spark when it won't start ?
Could be a relay or coil, ignition module, or other component.

thinc u should hav a residual fuel pressure test-its done on the engine fuel rails--pump and relay could also be checked

Check your starter and check your connections to make sure they are clean and tight. The low fuel pressure won't cause a no crank. Too low could cause a no start but not a no crank. I've had starters be bad right out of the box. But if that starter motor isn't turning either the starter motor is bad or the solenoid attached or the wiring to it is at fault.

Hi, had same problem with my truck. you need to replace your fuel pump because it no longer holds the pressure in your fuel rail. If you cycle your ignition on and off multiple times(this will cycle the fuel pump relay) with out turning over the engine then start it normally, that is the problem.

Check fuel pressure at schrader valve on fuel rail while key on and engine not running. Spec is 55 to 61 PSI. If it is lower than 55 PSI, replace fuel pump and fuel filter.

Possibly flywheel. Next time it happens, put car in gear, handbrake off, rock the car back and forth then try again.

your statement is "my jimmy won't turn over"
why are you concerned about the fuel pump?
the fuel pump only supplys fuel to the injectors while the engine is cranking over & runing. You should be looking at a dead battery or faulty starter. Its also possible the engine is locked up. But I would start by trying to jump the battery. If the starter is starting to fail, sometimes you can use a small hammer and lightly hit the starter while someone else is turning the key, this method can be dangerous to the person under the car so be carfull, but it can cause the starter to rotate enough to catch and crank the engine over properly.

If your concern is that the engine is cranking over & wont start, that a different issue.
Your truck does not have a fuel shut off like some Ford products. You can simply depress the shreader valve in the fuel line while the key is on & you should get a lot of fuel to spray out. This would indicate the pump is working and the problem maybe electrical, no spark.

bad battery conection or fuesable link

please clarify does it start or not ??