260 help help help bogging problem

[tangerine386]

my reg is in stock location my pressure is 55lbs before its regulated and it is a gold 39lb reg however its not a bosch it a aftermarket copy 30$ so maybe not working correct but why would it run great at first then act up is what confusing

[roadkill636]

Did you do something to the regular to get it up to 55#s? Smash the spring? Is it pre set or adjustable?

[2015Duramax]

my reg is in stock location my pressure is 55lbs before its regulated and it is a gold 39lb reg however its not a bosch it a aftermarket copy 30$ so maybe not working correct but why would it run great at first then act up is what confusing

As stated earlier it may run fine at first then the ECU reads to much fuel pressure and goes fat ! correct the fuel pressure problem and go from their . As you keep saying the cheap regulator my be the problem but you want know until you swap it out , but the bottom line is you need 39psi at the injectors not 55psi .

[BUZZIN' DOZEN]

Does this motor still have the TPI switch on? a '93 should have come with one.

[roadkill636]

Also you have Promax A17 ecu with crank case injectors. There could be a problem here. What injectors do you have?

[tangerine386]

yes does have throttle position box on it stock injecters this was a running motor that would push the boat into 90s the motor sat for five years could the old ecu be marked a17 and have somthing else in it it did same thing with old ecu fuel pump and old reg changed all to new still does it also that is correct ecu according to parts diagram od181275 model 93os 1925241nh L model

[CI STV]

Did you buy the regulator new or from someone else? Could someone have modified it? It’s quite easy to increase the pressure in those style of regulators by using a socket on top of it and tapping it to increase the tension on the spring. That’s an old trick the Buick GN guys used to do back in the late 80s early 90s to increase fuel pressure to forego a fuel injector upgrade.

[tangerine386]

brand new regulator but it was supposed to be a bosch replacment part the 39lb bosch was used in 70-80 volkswagens and jaguars when u cross ref part numbers i might have a bad ground wire somewhere messing with ecu as someone else has said

[2015Duramax]

brand new regulator but it was supposed to be a bosch replacment part the 39lb bosch was used in 70-80 volkswagens and jaguars when u cross ref part numbers i might have a bad ground wire somewhere messing with ecu as someone else has said

You will just be chasing your tail until you correct the fuel pressure issue . At this moment we know that it is not correct and you need to eliminate that as a cause before jumping to something else .

[BUZZIN' DOZEN]

yes does have throttle position box on it stock injecters this was a running motor that would push the boat into 90s the motor sat for five years could the old ecu be marked a17 and have somthing else in it it did same thing with old ecu fuel pump and old reg changed all to new still does it also that is correct ecu according to parts diagram od181275 model 93os 1925241nh L model

Does the box have 2 plugs and use the tpi? those were very problematic when new let alone 27+ years old.

[FUJIMO]

...a fully charged healthy battery is critical with a 260 efi...

[tangerine386]

yes the box is two plug and tpi i run 2 battieries wired as one big battery 1000amp 650 amp always charge them night before i think im to the point where im just going to get rid of it whole thing or part out

[mercrazy]

when mine was doing that, it was the ecu.
it would go stupid rich.
put on an ACU and no more problems.

[tangerine386]

i did get a differant ecu but it may be bad too im think im done with it

[FUJIMO]

...turning on & off battery switches when charging can hurt ecu's sometimes also... in other words, they don't like voltage surges...