350 mag mpi hard start only after first time

[silver_power]

Hello, i have a small problem (again) with my engine 350Mag Mpi (1A348183). It starts perfect at the first time of the day but every other time it crank for 1-2 second more than normal, idles for about 2sec at about 250rpm and then it idles at 550rpm steady and perfect. For example, yesterday, i started the engine for the first time , started perfect, and turned it off at about 30secs.If i start it again immediately, it will start perfect agian. But if i try to start it at more that 5mins (10mins, 30mins, 3hours 5hours etc)it will start again with low idle for about 2secs and then perfect again. It is totally tuned up and runs perfect. Yesterday i made a test...after i turned the engine off, i let the throttle at wot for about half an hour (in case of flooded engine) and started after the engine. It crancked normally for 2secs as usual and it fired it up. Offcourse i pull back the throttle and the engine idled perfect again. I think that the fuel injectors leak and flood the engine while it is stopped, but first i have to say that during idle there is no smell of gas and second i do not have higher fuel consumption than i used to have. At the start of this summer season, as i had some other performance issues, i had checked fuel pressure and it kept about 40psi for at least 2mins which means no leaks and also i checked the injectors to a professional and cleaned as well and he told me that they were in very good condition..........I had not had the fuel pressure gauge yesterday to check it again, only the diacom which confirmed that i had no active faults, but is it possible to have this symptom caused by a leaky injector? Shouldn't i have any more symptoms? Next time i will go to boat i will have the pressure gauge to check but is there anything else i can check?

 

[silver_power]

New summer season and the problem is still the same.......i Just made a test. I fitted a fuel pressure gauge at schrader valve and turned the key to "on" position .the fuel pressure after the pump stoped was 38psi. I recorded the fuel pressure at one minute intervals from 0 to 10mins. The results was the following.
0 min 37psi
1 33
2 30
3 29
4 29
5 28
6 26
7 25
8 24
9 23
10 22.
The system lost about 1bar (14psi) of pressure in 10 minutes. Is this fuel pressure drop normal? If this is bigger than normal and have an injector leakage it explains the symptom. But if not then I must look somewhere else for the problem.
if anybody has an experience in the fuel pressure drop to tell if my case is normal.....it would be helpful.

 

[QBhoy]

Hi
if nothing else...get a new diz cap on it ASAP. If it’s not that...it will be soon. Other than that an IAC might do the trick. But when my iac failed it was very obvious and beeped an alarm. Go with the Diz. Won’t do you any harm

 

[silver_power]

I already changed the dizzy and nothing changed.......same problem. So you think that the pressure drop I have is normal and nothing wrong with my injectors??
I think that iac make that trick because if I give a little throtle during cranking it will fire immediately and smooth idle. ....is this a kind of sign?

 

[Scott Danforth]

based on your serial number, you should be at 43 psi

you got a fuel pressure problem

 

[silver_power]

But the engine seems very strong and can get 5100 rpm with 56-58mph@gps.....how can I have fuel pressure issue. ..??

 

[QBhoy]

But the engine seems very strong and can get 5100 rpm with 56-58mph@gps.....how can I have fuel pressure issue. ..??

Does your alarm beeper work ? Does it sound when the key is turned ? Just wondering if it’s broken and you do have a iac issue.

 

[silver_power]

Yeah. ...the beeper sounds good.
I think that I have iac problem. It is possible that iac stay initialy closed while engine is warm ,during cranking since the duty cycle of iac in this situation is low. Injectors give the fuel but there is no air due to the iac and so the motor floods. I think that this may happen because the engine starts fine if I push the throtle a little and air passes from the butterfly.
one another thing I noticed.: while the engine is warm @idle, rpms are steady at 550rpm but the spark advance fluctuates from -3 to 9 degrees and the available power is about 60-70% with no active faults. As soon as I push the throtle at about 1200 rpm, the spark advance is steady at about 13degrees and the available power 100%. I think that engine cannot controls idle rpm totaly with iac valve and changes the spark advance. I have already buy a Ford windstar iac valve (hitachi abv0006) and I am waiting for it. After all, I still use the original Iac valve and the motor is 9 years old with 500 hrs. I think that it is a long time for the standard iac valve and it worth to try another one after about nine years.......

 

[rock doc]

I had a loose hose clamp on the fuel pickup side - it would idle fast and stall out randomly. Tightened up the clamp and no more issue. Hopefully it is something simply like that...