Wants to stall under throttle at first start up

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#51

10-21-2018 | 05:23 PM

GeorgeLG

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Joined: Jan 2007

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From: Florida

The most accurate test is probe the gray wire and the black pump ground wire, both right at the pump during KOEO and the pump running and tell us what that actual net voltage is as the pump sees it

#52

10-21-2018 | 05:25 PM

ajfetterman

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Posts: 42

That is what I used. Big black wire and the grey. Also checked with a chassis ground as well. Both gave me the same results.

#53

10-21-2018 | 06:02 PM

GeorgeLG

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Posts: 4,309

From: Florida

If that is while the pump was running then you don't have a ground problem. If you did then those two tests would vary significantly. It appears that you have good power to the pump. There are rare and strange power problems that can occur such as a marginal connection that does not show up until more current/heat flows through it but it's unlikely. Repeating that test a handful of times in a row can help rule that out if you want to be extremely thorough.

George

#54

10-21-2018 | 06:35 PM

ajfetterman

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Good to know. I did I’d say 4-5 tests on each ground.

So in your opinion, stay the course and buy the Delco pump?

#55

10-21-2018 | 07:10 PM

GeorgeLG

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From: Florida

Yes I think your ready for the new pump at this point. Fingers crossed.

George

#56

10-21-2018 | 07:11 PM

ajfetterman

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Thank you. Fingers crossed for sure.

#57

10-26-2018 | 06:06 PM

ajfetterman

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So new pump showed up yesterday and I installed it tonight. Soldered the splices this time.

I can report that fuel pressure does hold. I tested under the hood. Still only goes to 50 while at idle but it does hold now after I turn the key off.

STFT B1 3.1%
LTFT B1 25%
STFT B2 2.3%
LTFT B2 23.4%

Admittedly it runs slightly better without the hesitation I was getting, but it still isn’t quite right. And I still have P0171 & P0174 codes. I cleared them when I packed up for the night so I guess we’ll see tomorrow if they come back.

Any other ideas on the long term fuel trim being so high?

#58

10-26-2018 | 06:56 PM

GeorgeLG

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Posts: 4,309

From: Florida

Did you perform the fuel pressure tests in the sticky? What do those numbers look like - Key on, engine off, pump on and key on, engine off, pump off and holding?

George

#59

10-26-2018 | 07:30 PM

ajfetterman

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Only tested under the hood, not at the filter tonight.

I suppose that I need to do that and move on from there.

#60

10-26-2018 | 07:35 PM

GeorgeLG

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Joined: Jan 2007

Posts: 4,309

From: Florida

I am actually suggesting these tests at the fuel rail Schrader on top of the engine. We need to confirm that at key on with engine off that the rail at the engine develops 60-66 psi and after the pump stops priming and the engine is still off that the system can hold 55 psi for ten min. Once we have established that this is the case then we can move on to other issues. At this point we still don't know if your fuel system pressures are 5x5.

George

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