98 SL1 Stalls at cruise speed?

[Ksmcuda]

Okay here goes...
My Saturn aparently got some bad gas. It was stalling anywhere and anytime. The dealer cleaned the tank,lines, injectors,etc. The fuel filter was replaced and also the coolant temp sensor. An engine mount was also replaced due to need.
-No problem- I thought this would solve everything.
BTW New plugs and wires were added
This thing runs smooth as glass.
***When the car really warms up, it will stall like it has no gas.***
A minute or so later it will start and run for awhile
This happened along the interstate going 70 or so. Right before it stalled, I noticed some knock or pinging.
The dealer had stated that the pump seemed fine. It reminds me of Vapor Lock??? What may be causing a vapor lock condition?
Check engine soon light is now on.

Other info. NO codes were found.
165,000 miles
Well maintained
Otherwise, runs great...37mpg still
Thanks in advance
Kevin

[sierrap615]

hate to say this but i had to research vapor lock a little....

gas vapors are caused by heat in the fuel system causing the gas to boil. heat is generated by the plusing of the fuel injectiors and the electric motor in the fuel pump. heat can also be absorbed into the fuel lines by any of the many under hood heat sources(engine, trans, radiator, exhaust, ect) vapor lock is less like on a fuel injected car to two reasons. 1- the pressure is higher so the gas is harder to boil and its easier for the fuel to overcome the vapor. 2- a return line is commonly used torecurculate and help cool the fuel.

what was the first year saturn used a fuel system without a return line? 1998.

with that being said, and you saying it only happens when hot i would say vapor lock is very unlikely, but possible.

what to do: check to make sure the fuel lines haven't been improperly rerouted near heat sources(the only real heat sources i can think of in that area would be the heater hose and the metal lines to the TXV(part of the A/C system, mounted on firewall)), keep your fuel tank on the fuller side of 1/2 (get all the dirt out fuel and help keep it a little cooler), get gas from a quality gas station(Mobil, BP/Amico, or Shell only)

the knock/ping *MAY* be from high combustion chamber temps caused by a combo of carbon deposts and running lean(lack of fuel).

this - http://www.saturnfans.com/forums/showthread.php?t=25237 - will remove the carbon deposts if that is the case. easy and no cost, why not try it?

after that, i have two other thoughts - the PCM(computer) may still be set to the old fuel trim/map settings. cleaning the injectiors and replacing the ECT will change how the engine preforms by themselfs, but the PCM is still injecting fuel by how the engine was running before. the PCM can relearn by itself, but it would take time, to speed up the relearning, you can reset the fuel maps by pulling the PCM B fuse for about 15 seconds. second, the electrical resistance of a bad injectior can change when it becomes hot, if that happens, the PCM may shut down to protect itself until the resistance returns to normal.

long story short, i don't know whats wrong for a fact, these are all just ideas. you may want to repost on saturnfans.com, folks smarter then me are there.