03 xls, hot start issue, 4.0 v6

[zipchip]

Hi Folks, new to the Explorer forum. Having a hot start issue. Bought it 45 days (135k) ago, 1 owner garage kept very clean replacing my '94 Ranger XLT. I recently replaced the original fuel pump which failed (used a Spectra Premium SP2008M Fuel Module + new filter). Since the pump was replaced (btw fuel tank was very clean), whenever the engine is hot, 9 out of 10 times I noticed that the engine cranks 4-6 seconds, before it starts (and it always starts with the new fuel pump). When cool, engine starts immediately. Suggestions on where to start looking? Could it be the coolant temp sensor? Any way to bypass sensor to test before I start buying parts? A vapor lock issue? No knowledge of age of plugs, wires coil pack, etc. Thanks.

 

[SoCal2V]

Cycle the key from Off to On without cranking the engine, do this 2 or 3 times (leave in On position 1 to 2 seconds each time) and then attempt to start.

Did it fire right up?

If so, suspect fuel pressure leakdown. It happens due to a faulty check valve in the fuel pump. You wouldn't be the first guy to have bought an aftermarket fuel pump that was faulty right off the shelf. This is one of those parts where I would recommend oem/Motorcraft replacement if at all possible - haven't looked but I'm willing to bet you could find one at RockAuto.com for a reasonable price.

Anyway, try the above a few times and let us know how it goes.

 

[zipchip]

Thanks SoCal, will try that process, my buddy also told me something similar, turn the key to ON and listen for the fuel pump to prime, then crank, so far so good seems better, not instant when hot start but much better. Thoughts? does this mean a faulty pump?

 

[SoCal2V]

^ If that's working for you fairly consistently then yeah, faulty pump is very likely.

 

[zipchip]

SoCal, I have a call with Spectra tech tomorrow, what is the issue specific to the hot engine that could be the issue? The fuel pump does not know the engine is hot. So if the check valve is not holding pressure correctly within the pump when turned off, that should be an issue with hot or cold engine? What am I missing? Thanks.

 

[MrQ]

Did you check the fuel filter?

 

[zipchip]

Did you check the fuel filter?

Yes filter replaced.

 

[zipchip]

SoCal, spoke to Spectra tech support, they said since the issue occurs on hot engine condition, of course they don't feel it has anything to do with their Spectra pump. They suggested I check fuel pump pressure at start and idle, should be 65psi +/- 8psi to be in spec. Whats yr opinion on Bosch fuel pumps? Motorcraft kinda pricey even at Rock. Thanks.