Tahoe 2007 starts rough and smells like gasoline

[DJPoertsch]

Good morning dear friends from the forum.
I wanted to talk to you about whether my assumption was correct. My Tahoe 2007 with currently 424800 km starts very unsteadily after standing for a long time and then smells like petrol. It only runs for about 5 -10 seconds and then it's quiet. No problems even while driving. No check engine light on.
I now suspect that an injector is leaking and that's why I have a rough start and also the smell of gasoline. Can you confirm this or is there perhaps another issue? I would be happy if we could narrow down the issue together.

Best Regards from Germany

Markus

 

[mikez71]

That would also be my guess..

 

[rdezs]

Before diving into the injectors and whatnot, pull your EVAP purge solenoid off the intake manifold... If you can blow air through it, it's stuck open and flooding your intake with fuel vapor creating an overly rich mixture. At your mileage, I'd go ahead and just replace it, they're not expensive.

 

[07burban88]

this is true when ignition off purge valve should be closed

 

[LsHart]

I read this and thought of I am gasoline Kicking Harold.

 

[DJPoertsch]

Thank you for all the feedback. Today I'm in the car repair shop and will check everything. Since I have technical inspection service here in Germany next week, it is a good idea to check the things at the same time. I will give you feedback when I know something about it. Thank you

 

[dkad260]

How many miles on the plugs? Are they OE AC Delco or aftermarket?

 

[goldpack]

you can also get some dye. similar to the dye they use for HVAC and coolant.

it would be labeled for oils, fuels, brake fluid. putting a little bit into the fuel tank may show a physical leak on the incoming line.
and with gasoline ...little drips dissipate so fast all you get is a smell and nothing to find. ...so the florescent dye will pop up fast.

..used the same 10oz bottle for 20 years as I use so little. ...but great at finding which rubber or steel line is rusted or loose....vs. all the others that only look bad.

 

[DJPoertsch]

How many miles on the plugs? Are they OE AC Delco or aftermarket?

They are about 25000 km because I drive with LPG and Iridium NKG Spark Plugs. I Ordered already ACDelco Iridium I will replace them next week.

 

[DJPoertsch]

Thank you so much for all your feedback.
I apologize for waiting so long to reply, but I had a family emergency.

Here's an update:
I removed the valve, and it's undamaged. I've noticed that the jerking gets worse the longer the car sits. I really suspect it's the fuel injectors. I should mention that I only drive on gasoline for the first 2-3 km. After that, my Prins LPG system kicks in. Therefore, I only experience these problems when starting the car and after it's been sitting for a while. I think the idea of adding dye to the fuel is brilliant. I just need to find out where I can get it in Germany. I'm always open to other suggestions. Thank you all for your fantastic support.

Also I will replace first all 8 Sparkplugs. For you all never the Motor Control Light was coming on. So I have no failure Codes.

 

[j91z28d1]

is this a flex fuel vehicle that can run on e85? I don't know anything about what gm did for other country market vehicles, but here if they are flex fuel that can run e85. sometimes the ethanol content gets messed up in the ecm, and it will thing it's runny e85 when it's on gasoline and run pig rich. with a scanner you can read what the ecm thinks the e content is. and reset if it wrong.

 

[DJPoertsch]

is this a flex fuel vehicle that can run on e85? I don't know anything about what gm did for other country market vehicles, but here if they are flex fuel that can run e85. sometimes the ethanol content gets messed up in the ecm, and it will thing it's runny e85 when it's on gasoline and run pig rich. with a scanner you can read what the ecm thinks the e content is. and reset if it wrong.

No it's an regular LTZ imported from US to Denmark and then Germany. It is no flex Fuel only regular gas with an installed LPG system. In time when I start it's a very ruff start and you smell gas very much. After 15 seconds it getting in normal mode with no issues. Only when he is parked long time you have this symptoms. So I guess that some injectors a leaking and dripping gas in the cylinder..

 

[me51]

In time when I start it's a very ruff start and you smell gas very much. After 15 seconds it getting in normal mode with no issues. Only when he is parked long time you have this symptoms. So I guess that some injectors a leaking and dripping gas in the cylinder..

That guess sounds very plausible. Can you turn the LPG system off and drive on gasoline for a few days to give the fuel injectors some exercise?

I know that the intake manifolds on these cars can leak occasionally which will cause mixture error codes and rough idle when hot. Repairing that is not too difficult, just time consuming and the space to work in is kind of tight especially under the cowl. Fel-Pro MS98016T is an improved part compared to the OE GM gasket set.

regular gas with an installed LPG system

I would never buy a car that has a system like this installed aftermarket. They often cause issues and barely anyone can really diagnose them. When these systems are installed the spark plugs are often changed to a colder heat value, holes are drilled into various intake pieces, sensors get "black boxes" connected in between, wrong settings in the LPG module burn the exhaust valves and so on. For the original ECM the car looks like it runs on regular gasoline.