Hard Start only when warm H2 2003

[Ulrich1]

Anyone,

My 2003 H2 is hard starting when warm. Only warm everyday. Dealer hooked up computer and said it was a pluged converter, and the scanner showed low battery voltage. Fixed converters and replaced battery yesterday. Today replaced the fuel pump and sender before I return to the dealer. Drove 30 minutes, went to restart-same problem, hard start. The hard start continues to get worse.

I do hear a little air hiss, that started right before the hard start issue. That's what made me think that it possibly was the converter. "Sounds like the air cleaner is off when I hit the throttle". Does a leaky intake gasket cause hard start warm but not cold?

Any suggestions?

[mikejr]

Originally Posted by Ulrich1

Anyone,

My 2003 H2 is hard starting when warm. Only warm everyday. Dealer hooked up computer and said it was a pluged converter, and the scanner showed low battery voltage. Fixed converters and replaced battery yesterday. Today replaced the fuel pump and sender before I return to the dealer. Drove 30 minutes, went to restart-same problem, hard start. The hard start continues to get worse.

I do hear a little air hiss, that started right before the hard start issue. That's what made me think that it possibly was the converter. "Sounds like the air cleaner is off when I hit the throttle". Does a leaky intake gasket cause hard start warm but not cold?

Any suggestions?

Reach out to Hummtech on this forum. He knows his stuff.

[Rico001]

Originally Posted by Ulrich1

Anyone,

My 2003 H2 is hard starting when warm. Only warm everyday. Dealer hooked up computer and said it was a pluged converter, and the scanner showed low battery voltage. Fixed converters and replaced battery yesterday. Today replaced the fuel pump and sender before I return to the dealer. Drove 30 minutes, went to restart-same problem, hard start. The hard start continues to get worse.

I do hear a little air hiss, that started right before the hard start issue. That's what made me think that it possibly was the converter. "Sounds like the air cleaner is off when I hit the throttle". Does a leaky intake gasket cause hard start warm but not cold?

Any suggestions?

Hate to say I have no idea what it is but from all the "miss" information you have from the dealer already it really sounds like they have no idea either.

Please tell me you have an extended warranty and you are not shelling out big bucks at the dealership service department for all the repairs.

I would suggest that you try a auto parts store that does scans for free and get a second opinion at least, and if they give you a print out you could compare it to the dealers if you go back there.
Good luck to you~Richard

[Ulrich1]

Hope they will rescan at no charge. The service advisor was out today.

I took care of the cats and changed the fuel pump myself. I purchased the fuel pump from Bennett Auto for 288.00-A/C Delco. Hummer wanted 400.00 and did not have one in stock. Advance and Napa wanted same price as Bennett but did did not have it in stock.

I'm thinking it is the injectors

[HUMTECH]

Could be a bad ect sensor. If its reading -40c(default temp) and your starting it warm the pcm will see that its cold and demand more fuel causing a hard start. Get them to check scan data and look for abnormal sensor readings.

[Ulrich1]

Originally Posted by HUMTECH

Could be a bad ect sensor. If its reading -40c(default temp) and your starting it warm the pcm will see that its cold and demand more fuel causing a hard start. Get them to check scan data and look for abnormal sensor readings.

I will replace the ect sensor.

Do you know where I can purchase dummy 02 sensor plugs? When I emptied my cats check engine light obviously stays on?

[HUMTECH]

Try Casper Electronics, i got a set of cheaters from thm for my 98 z71. About the same price as o2 sensrs and never had a problem with them

[Ulrich1]

Originally Posted by Ulrich1

I will replace the ect sensor.

Do you know where I can purchase dummy 02 sensor plugs? When I emptied my cats check engine light obviously stays on?

Changed ECT sensor today-No change in starting problem.