I'm running a L28 with DCOE 42s and fuel is supplied by an engine bay mounted Spectra Sp1141. Pressure is regulated to 4psi and there's a new fuel filter before the pump. Engine compression is great. No vacuum leaks or fuel leaks to be found.

 

Car idles and runs great, but for a hesitation from idle to acceleration. The car will pull to highway speed no problem.

 

The mystery is that on a long sustained hill it starts popping and has a hard time going. My guess is it is going lean as it starts popping and then hesitating. As soon as the car is on level ground it's fine again. This is with 1/2 a tank of gas.

 

Any ideas or diagnosis suggestions would be appreciated.

 

Thank you.

 

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1 hour ago, jitenshakun said:

The mystery is that on a long sustained hill it starts popping and has a hard time going. My guess is it is going lean as it starts popping and then hesitating. As soon as the car is on level ground it's fine again. This is with 1/2 a tank of gas.

Kind of looks like you're looking for affirmation of a thought.  Fill the tank and see if the problem stays.  These tanks are known for pinholes in the internal outlet tube.

How steep is the hill, and how long is the sustenation?

The hill is 8 blocks long and it really kicks in after 4-6 blocks and lasts until I've been flat for about a block. Maybe less? 40m-50m elevation change.

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It sounds like it is going lean as you say. The fact that it takes 4-6 blocks to come on and another block to recover suggests its fuel supply not jetting (as ZH says).

Another test would be to stop on the hill when the problem happens and see if it struggles to idle.

 

 

Lots of hills nearby so I'll try a few before I fill the tank and try again.

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@Zed Head@jonbill I idled on a steep hill without any problems and drove up 1 block long steep hills, again with no symptoms. Same 1/2 tank of gas. My next step will be a full tank and the longer hill that's caused me problems.

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Electric pumps like this work best as pushers.  Try moving the pump to the rear by the tank and see if that helps.

Electric pumps like this work best as pushers.  Try moving the pump to the rear by the tank and see if that helps.

Good tip. I'm going to do that this winter and swap out the cheap-o pump with a better unit.

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