Car harder to start after sitting 15min

[liquidzorch]

Originally Posted by Occasionally6

Before I read any of the posts, just the thread title, I was thinking: "The injectors are leaking.". After reading the posts, I still think that.

It only started after the injectors were cleaned, right?

One way to check is to pull the injectors, wipe their tips clean and pressurize the fuel system (run the fuel pump). After they have sat for a few minutes, wipe the injector tips with a facial tissue or toilet paper. That will show up even a small leak.

Do make sure that the injectors won't blow off the rail when subject to fuel pressure and in free air. Most are OK to do that with but if they're not, you'll have to wire them in place.

That is a good idea. It did start to do this on the same day I took the injectors to be cleaned. They did tell me that they were fine, maybe they didnt check them long enough.

I do know that the injectors will not stay in the fuel rail with the fuel pressure, so it is going to be hard to test, especially having to leave them pressurized for 15min. When I get time to check them I will. Thanks

[cbaber]

When you re installed the fuel injectors, did you use new o-rings and seals? There are o-rings that seal the injector to the fuel rail, and rubber seals that seal the intake manifold to the injectors. If you haven't done this you could have a vacuum leak and/or small fuel leak. You should replace these if you didn't already.

I took my fuel rail off just to clean my EGR passages one day. Upon re installing everything, my car would not idle and ran rough. Turns out even though the seals looked fine, I need to replace them. They cost < $10 OEM from Honda and fixed the vacuum leak.

[Miller88]

Try this when you go to start it hot - turn the key from off to run (not start) 4 - 5 times. That will cycle the fuel pump and "fill" the injectors if they have leaked. If it starts right up, you're losing fuel pressure - likely through the rebuilt injectors.

On a hot day, my Cherokee will heat soak and boil the fuel in the injectors. My solution is to hold the pedal 3/4 of the way down and race it at 3000RPM for 20 seconds, then it's fine. The mechanical fan really makes a lot of noise at that rpm!

[liquidzorch]

Originally Posted by Occasionally6

Before I read any of the posts, just the thread title, I was thinking: "The injectors are leaking.". After reading the posts, I still think that.

It only started after the injectors were cleaned, right?

One way to check is to pull the injectors, wipe their tips clean and pressurize the fuel system (run the fuel pump). After they have sat for a few minutes, wipe the injector tips with a facial tissue or toilet paper. That will show up even a small leak.

Do make sure that the injectors won't blow off the rail when subject to fuel pressure and in free air. Most are OK to do that with but if they're not, you'll have to wire them in place.

Finally I got to checking the injectors. 2 were leaking a little when turning engine off. I sent all of them back to the lab and they cleaned them again. Now engine starts up fast every time.

Thanks to everyone for the help

[user removed]

Put a fuel pressure gauge on the rail and check the pressure under the conditions when it is hard to start. Possibly the fuel pressure regulator has a leaking diaphragm and it is draining fuel into the intake manifold.

Nissan Z cars were terrible about hot soak restarts. On the later models they put an injector cooling fan to blow air on the injectors, which helped some but never really cured the problem.

Another thing to try would be to clamp off the vacuum line to the regulator when you stop it hot. The unclamp it just before you try a restart.

regards
Mech

[liquidzorch]

Originally Posted by Old Mechanic

Put a fuel pressure gauge on the rail and check the pressure under the conditions when it is hard to start. Possibly the fuel pressure regulator has a leaking diaphragm and it is draining fuel into the intake manifold.

Nissan Z cars were terrible about hot soak restarts. On the later models they put an injector cooling fan to blow air on the injectors, which helped some but never really cured the problem.

Another thing to try would be to clamp off the vacuum line to the regulator when you stop it hot. The unclamp it just before you try a restart.

regards
Mech

Thank you for helping. I have already fixed this issue. It was leaking injectors when off.