injector install ?
Thread Starter
Racer
Joined: Sep 2011
Posts: 445
Likes: 11
From: Indiana
injector install ?
Hi guys. 89 auto. In the middle of injectors swap while installing SR. Question is I installed Bosch III from FIC and put injectors in, then installed fuel rail, hooked up two fuel lines to check for leaks. No leaks it appears but when I put fuel pressure gauge on pressure starts dropping from 40 and on almost immediately. I thought fuel pressure should stay strong? That's why I swapped injectors cause pressure wasn't holding. Any help would be much appreciated.
Ron
Ron
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
There is a check valve and pressure regulator in the fuel pump that can leak when the engine isn't running.
As long as it maintains pressure while running you're OK. <-- others may have a different opinion about that... ;-)
As long as it maintains pressure while running you're OK. <-- others may have a different opinion about that... ;-)
Thread Starter
Racer
Joined: Sep 2011
Posts: 445
Likes: 11
From: Indiana
Well I ended up popping off the belt tensioner to access the rubber fuel lines to clamp off to try and figure things out. My buddy helped cause fuel pressure drops fast. First we primed system and clamped fuel feed line line. Pressure still dropped. Then we did fuel return line. Pressure dropped. So then we clamped off both lines. Pressure still drops which leads me to believe the injectors are still leaking and there refurbished Bosch III from FIC. Any body tell me if im doing something wrong here?
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
I agree with Cliff..
the pump ball-check is there for when you stop, so the system holds fuel tension for a while. This is helpful when you go to start up again in the next few hrs the system will still have some tension so the pump does not have to fill the rails and the whole fuel system. BUT, if it leaks back or "bleeds-off" rapidly, like in less than 1 hr, thats bad because now the KEY-ON must re-charge the entire fuel system and this may require longer cranking times when the pump is only allowed to run for 2 seconds...thats NOT enough to refill and charge the system with some pretension for good injector cycling as the engine is cranked...result, longer cranking
The pump bleed back may or may not cure itself. It happens then goes away. Run some Marvel MiniSeries oil thru the tank. About 1 bottle to 8 gal or more of gas. This will make everything work better, even an a pump thats got a stuck check valve.
the pump ball-check is there for when you stop, so the system holds fuel tension for a while. This is helpful when you go to start up again in the next few hrs the system will still have some tension so the pump does not have to fill the rails and the whole fuel system. BUT, if it leaks back or "bleeds-off" rapidly, like in less than 1 hr, thats bad because now the KEY-ON must re-charge the entire fuel system and this may require longer cranking times when the pump is only allowed to run for 2 seconds...thats NOT enough to refill and charge the system with some pretension for good injector cycling as the engine is cranked...result, longer cranking
The pump bleed back may or may not cure itself. It happens then goes away. Run some Marvel MiniSeries oil thru the tank. About 1 bottle to 8 gal or more of gas. This will make everything work better, even an a pump thats got a stuck check valve.
Thread Starter
Racer
Joined: Sep 2011
Posts: 445
Likes: 11
From: Indiana
Even though I clamped off the fuel return line and pressure held?Wouldn't pressure leak past the check valve back in the tank? When we cleamped both feed and return line pressure still dropped fast. Just like the video of FIC youtube. Which makes me think a injector.
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Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Not nessasarily, the gas can lock the check valve as it should...or it may allow it to free-flow as if there were nothin there. These things can stick or work as they are supposed to. Hard to say.....
Clean, test, reassemble and see just how bad it is. If you get it working, leave it to test and chances are it will be ok in real world conditons,`
Clean, test, reassemble and see just how bad it is. If you get it working, leave it to test and chances are it will be ok in real world conditons,`
Le Mans Master
Joined: Feb 2005
Posts: 6,475
Likes: 565
From: Clearwater Florida
............ How does your car run ? ... How did it run ? ..... Pressure bleed-off is inevitable because the pressure regulator has a metal to metal seal ......... so if it runs OK and holds pressure while the engine is running you are good to go ...... the new injectors likely weren't a necessity but it didn't hurt to change them ... fuel pressure leak down is not a problem in and of itself but is an issue for some forum members ..... proper diagnostics will save you time and money every time ..........
Thread Starter
Racer
Joined: Sep 2011
Posts: 445
Likes: 11
From: Indiana
............ How does your car run ? ... How did it run ? ..... Pressure bleed-off is inevitable because the pressure regulator has a metal to metal seal ......... so if it runs OK and holds pressure while the engine is running you are good to go ...... the new injectors likely weren't a necessity but it didn't hurt to change them ... fuel pressure leak down is not a problem in and of itself but is an issue for some forum members ..... proper diagnostics will save you time and money every time ..........
Le Mans Master
Joined: Feb 2005
Posts: 6,475
Likes: 565
From: Clearwater Florida
Car ran like **** before injector swap. Found gas in my oil. Cracked TB open and it smelled like gas. Pulled AFPR vac line no gas. Car is not back together as I installed SR as well. Just the plenum left to install. I will proceed with the install. Ill let you guys know. Thanks for all replies.