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Slow to start with bigger injectors

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Sam's GSX

5+ Year Contributor
394
54
Jun 10, 2018
Hohenwald, Tennessee
Ok, this is weird, my car has always taken a bit longer to crank then a normal car, but I was fine with that.
Then when I did a turbo swap from a cheap 20g (it came on the car) to a Borg Warner s256 it was still fine, then I switched to fic 850cc injectors (and set global and deadtime appropriately with dsmlink) and if the car has been sitting more than 4ish hours, it cranks for about 4 seconds, (a bit longer than before)
But is doesn't start right up, it catches like it's trying to start, after about 2 seconds of it catching it will start.
Has anyone had a problem like this? I have been needing to replace my fuel filter also, but I don't think that is the main problem (I have the fuel filter, I've just been putting it off for a while now)
 
I just thought it was semi-normal for larger injectors, I have pte 880s and it takes about 5-6 cranks for mine to start, occasionally longer when cold or I just stop and do another starter bump and it goes on the first crank by then.

In for any info.
 
Just check your fuel pressure whe you turn off the car, if it drops to fast then you have a leak somewhere and it wikl cause a long starting issue next time around, when you switch off it should ideally hold pressure for some time and some bleed it off faster and then holds as lower pressure.
 
Just check your fuel pressure whe you turn off the car, if it drops to fast then you have a leak somewhere and it wikl cause a long starting issue next time around, when you switch off it should ideally hold pressure for some time and some bleed it off faster and then holds as lower pressure.
Ok that's a good idea
 
I agree with Bobby, and maybe those different injectors are bleeding down. I know my auto car bled down kind of fast and had factory 390's in it. When I swapped over to my FIC 1120's, it held fuel pressure for a LONG time, almost a full day. I figured the old injectors were bleeding after seeing that. It was usually a 4-5 crank start up on the 390's but the thing would fire up much quicker after the injector swap for me. We did go to SD at the same time tho.
 
Ok, I had to move the car for an oil change so I tried the wot start, after that the cars still did the same thing, I only had to move the car 50 feet and I didn't want to heat the engine up to much, but as fast as I could turn the engine off and left the hood to check the fuel pressure, it had already gone down to 0. I'm guessing this is the problem, (unless it had to do with only running the car for a minute, but I doubt it)
 
Well, I bought it about 8 months ago to fix a problem, but I fixed the problem before it got here, and I've been wanting to do it but have always had something more pressing to do on the car, plus I've heard so many people complain about how hard it is to get the bolts to loosen
 
You should be checking pressure when CRANKING, not after it's running. All fuel pumps will bleed down over time, walbros tend to bleed off rapidly as the check valve in them sucks. Regardless of that it should still prime while cranking within half a crank or so. If it's taking longer than 1-2 full cranks to build base fuel pressure (43.5psi) you have a fuel flow issue with the pump or a restriction (filter etc). If you have 43psi of pressure and it stills won't fire, you have other issues such as injector settings, cam/crank sensor delay, etc etc. Find out your cranking pressure and how quick it PRIMES first.
 
I had the same issue before I rebuilt the head. Long crank on cold start and hot start was fine. Fuel pressure also dropped to zero after the car sat for about >30 minutes. I rebuilt my head because my valves didn't completely seat so I replace those intake valve and all exhaust valves. Also went with bigger injectors at the same time. Now the car starts like a champ, only a couple of revolutions sometimes just one and immediate. My fuel pressure still drops the same way as it did before. Think my compression before was 120 90 90 120. Now they're 120 on all 4, cold and dry compression. Maybe check the compression if all else fails.
 
One thing to remember is if you have an out dated version of dsm link the fuel pump does not turn on with the key, you have to click the starter before the fuel pump will start. But if you update your dsmlink to the newest update you will get the option to have the pump prime with the key in the on position. Best update ever!!!
 
I actually had tried turning the "fuel pump always on" option on, but did not help unfortunately, I even adjusted the "crankingfueladjust" a little, (which changes fuel with coolant temp) but with the same result. This is a real head scratcher, and I checked out that thread and it was helpful, infact I thought that's where my problem might be, but if turning the fuel pump on and the pressure goes up (I'll check that soon) than its probably not my problem because I had tried the fuel pump on already, unless the regulator is real bad, could a leaking injector do this? And do they mean leaking outside of the engine? Or inside the cylinder?
 
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