1990 D150 Fuel starvation issues

[Scargo]

Anyone have any recommendations for solving the Mickey Mouse fuel tank supply configuration on my 1990 D150? I think that the fuel cannister that goes into the tank (that houses the fuel pump and pre filter) is not filling quickly enough and causing fuel starvation at cruising speed and when stopping. Especially when fuel is below 1/4 of a tank.??? WOT and idle seem ok. Seems that the 1990 has a unique tank in that the 1991 tank is different. I have had the tank out 3 times, replaced the fuel pump with pre filter. and the external filter.

 

[captainchrysler]

If wide open throttle is fine then fuel delivery doesn't sound like a problem. The fuel pressure regulator might be the problem. I had a similar drivability issue in a 89 New Yorker and the regulator was the problem. Check the vacuum line going to the regulator, bad vacuum signal and it won't adjust the pressure correctly.

 

[Scargo]

OK. Thanx. I'll check it out. I have an extra TBI assembly that I have swapped out with the same problem. So problem seems external to the TBI ie vacuum issues. I just wonder about return fuel function back to this canister assembly in the fuel tank??? More news at 11, Thanx again. BTW, are you fluent in this 1st gen OBI diagnostics??