So I have a 1987 Volvo 740 turbo intercooler that has an upgraded turbo and Ecu(set for 18 psi)
It has 2 problems that I nor any of my mechanic friends can figure out.
1. It runs really rich, I just replaced both the fuel pumps and the fuel pressure regulator and it didn't fix it at all.
2. When the engine is warm it has an extremely hard time starting up again. I have to hold the key down for a minute or so while it it sputter and gets close to catching a couple times until it starts up. This is the problem that really baffles me I can't figure out why it starts up perfect cold but warm it takes so long.
Any ideas for either problem is extremely appreciated.

 

I'd change the Fuel Pressure Regulator. Hard hot start calls for that.

 

i wonder if the coolant temp sensor is sending the ECU or ICU an erroneous signal?

1987 is right at the end of the biodegradable ecojunk wiring era for Volvo... you could have crumbling wire harnesses, or maybe not (our 87 240 was late production and has been fine, but early production? eek).

there's a test procedure for the CTS that involves back probing the connector at the ECU when the engine is cold, and again when its warm, and also the ICU (the CTS has two sensors, one for each 'CU).

Does that 87 have a cold start injector? Those were dropped in later years... I wonder if thats stuck open? that would flood the engine making it run really rich.

for the CTS diagnostics, see https://www.volvoclub.org.uk/faq/Eng...ingECTFailures (and use the LH 2.2 stuff, as thats what you got).

 

Sorry, I missed that you changed the FPR already! Yes, the Coolant Temperature Sensor is something that may cause too much fuel if it sends a continuous "cold" signal to the ECU.