Hard start when cold

THUNDERSON1

MEMBER
1992 MAZDA TRUCK
4 CYL
4WD
MANUAL
110,000 MILES

B2600i: After the truck has been parked for more than 2 or 3 hours I have to crank the engine as well as pump the accelerator in order to get it to start. Truck is fuel injected so that one is hard for me to figure out. The longer the truck is parked the longer I have to crank it to get it started. Here's the kicker: Once the truck is started (after about 10 to 15 seconds of rough idle) the truck runs perfectly AND once it is warm it starts right up after turning off the ignition. I have performed 1) fuel pressure test: goes up to 45 while cranking 2) fuel volume test: passed 3)plugs replaced even thought the plugs in the truck show only normal wear 4)OBD2 shows no codes. I unhooked the MAF to force a code and it showed up so the ECM is reporting at least THAT code. Any ideas?

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Sounds like you may have either an injector leaking down or fuel pressure regulator flooding the engine. This would account for the rough idle (extra fuel in a few cylinders) and the need to open the throttle for more air. Try putting a fuel pressure gauge on it to see how fast it drops off when you shut it down. You can usually check the regulator by pulling the vacuum line off it to see if there is fuel in it, if so the regulator is blown

https://www.2carpros.com/articles/how-to-test-a-fuel-injector