I have and his suggestion was throw new coils and plugs in. I don't have the money for that right now. Tomorrow I will pull the plugs and check them out, they have 7-8k miles on them now running a 32 gap. I'll try to post pics of the plugs. Gonna give cleaning them a shot just to see.

Waiting to get my laptop this weekend to better view things, and email more logs to him to verify its not pump or tune related. If he can't find anything, guess new coils and plugs will be in the near future.

 

It could be the tune. There are a lot of parameters in the PCM for fuel pump pressure on the returnless system. You know they have to max out the fuel pressure to get the right flow out of the stock pump and with that same setting the new pumps are doing a much more efficient job of delivering fuel. I'd discuss it with a good tuner and get his input.

 

Well today I'm going to drop the tank and double check the pumps electric connections and make sure no hoses popped off. If one pump isn't supplying fuel for whatever reason then first and second would be running on the lean side like they are. If everything checks out ok today, ill start throwing datalogs at Jdm

 

Voltage tables on the twin pumps have to be adjusted in the tune. I will data log mine this afternoon to see what pressures I get. It's been to long since I did this. Back when I had a single pump the Whipple tune as well as custom tunes ran the hell out of the single pump to establish 65-70psi at WOT. With twin pumps this is not needed as the volume is there at the lower pressure. Hope I said that right. Anyway I will report back a little later.

 

Fatherford has this fuel system and also tuned with JDM,I don't recall him having this issue. But that's a good starting point double check everything.

 

Sorry to take so long to get back to you. Friday evening took a nasty little turn when I found my inboard exhaust manifold was full of coolant on my 1271 Detroit. Thank god it was just one engine and I hadn't tried to start it. Otherwise I'd be up a creek with a bent rod. Just have one hell of an engine flush ahead along with finding a manifold. Anyway back to the truck. Data logged this afternoon, fuel rail pressure at idle was 39psi and wot was 65psi.

 

Thanks for posting back. I've been to busy to look back here lately too. My old datalogs show 70 with the stock pump and 70 with the dual pumps so all good there. Been emailing with JDM, looks like the rich condition is the tune. I was just maxing out the stock pump making it look like it was running a perfect a/f when really the tune was commanding more fuel that it wasn't able to get.

Thanks for the help guys!

 

Thanks for posting back. I've been to busy to look back here lately too. My old datalogs show 70 with the stock pump and 70 with the dual pumps so all good there. Been emailing with JDM, looks like the rich condition is the tune. I was just maxing out the stock pump making it look like it was running a perfect a/f when really the tune was commanding more fuel that it wasn't able to get.

Thanks for the help guys!