Have a hard starting problem when hot and have decided to replace the fuel pressure regulator and also fuel injectors. The question I have is anyone send their injectors to be rebuilt or is it better to just spend the bucks and get knew ones?
If you're getting new ones, be sure they're flow-matched. Usually, when you have injectors rebuilt, they will flow-match them. I've been running rebuilt injectors from Fuel Injector Connection for about 35,000 miles with no noticeable issues. They were much cheaper than new ones, too.
If you're getting new ones, be sure they're flow-matched. Usually, when you have injectors rebuilt, they will flow-match them. I've been running rebuilt injectors from Fuel Injector Connection for about 35,000 miles with no noticeable issues. They were much cheaper than new ones, too.
What exactly does "flow-matching" mean to you?
To me, flow-matching means that you measure the flow of a large number of injectors, and you pick the six (for a 6-cylinder) injectors having the most closely matched flow rates.
I sent my 6 injectors for cleaning, and if they're close in flow, great. If they're mismatched in flow, too bad, there's nothing that can be done about it.
My injector cleaning place told me that one injector was damaged beyond repair, so I had to buy one replacement injector. That almost wiped out the cost savings of cleaning versus just buying new ones. And now, I don't know the flow rate of that replacement injector, unless I spend money to have it flow-tested. So I don't know how well flow-matched the replacement is compared to the other 5.
So next time I think I would just buy 6 new ones and save the hassle... Or a flow-matched matched set of 8, in order to have flow-matched spares.
That's what I was worried about. I may have a leaking injector or whatever and then I have to purchase one. Are remans flow matched as a set? Then I read something about dynamic testing at someplace being the real test. I don't know enough about this. I do know I will replace the pressure regulator while torn apart and fuel pump if that is the problem. As someone said this is a 31 year old car. Just trying to save money.
Flow matched to me means that all the injectors in a single engine flow the same rate of fuel. The same brand and part number injector might flow differently, but all injectors in a given engine should flow the same. At one time, Fuel Injector Connection had a video showing the testing procedure for flow. All the injectors were put into the test equipment and the spray was captured in a calibrated vial or tube. The spray pattern could be seen, and when the test was ended, total flow was compared.
There is no shortage of FI service outlets around, and they generally clean and test the injectors and give you specs on output. If any are substandard, just replace them.
First step is to confirm whether you have a leaky injector. Otherwise you may just waste money. A gauge on the fuel rail will tell you. As for rebuilt. It is not possible to rebuild a fuel injector as they are hermetically sealed. All you can do is clean and flow test them. As for cleaning there are kits available to do it on the car
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
FINALLY got the time to test the very slow leak on the fuel rail. Pinched the supply and return lines after 2 sec fuel pump start. Goes immediately up to 43 psi. It slowly drops down to - say 1 psi every 3-4 minutes with engine off. Engine on fuel pressure regulator rises 6 to 8 psi when vacuum removed and doesn't leak gas from vacuum line. Fuel pressure increases when revving engine and responds correctly with snap throttle rev. Have thought about getting another fuel gauge to be sure for leak. I think I have a harbor fright. Swear I smell a faint gas smell in oil stick. Would not be good at all. I have read about this till blue in the face. What does anyone think? About to tear into it. Car runs like a champ. Has to be A LEAKING INJECTOR RIGHT??????
FINALLY got the time to test the very slow leak on the fuel rail. Pinched the supply and return lines after 2 sec fuel pump start. Goes immediately up to 43 psi. It slowly drops down to - say 1 psi every 3-4 minutes with engine off. Engine on fuel pressure regulator rises 6 to 8 psi when vacuum removed and doesn't leak gas from vacuum line. Fuel pressure increases when revving engine and responds correctly with snap throttle rev. Have thought about getting another fuel gauge to be sure for leak. I think I have a harbor fright. Swear I smell a faint gas smell in oil stick. Would not be good at all. I have read about this till blue in the face. What does anyone think? About to tear into it. Car runs like a champ. Has to be A LEAKING INJECTOR RIGHT??????
If you smell gas in the oil then the engine could be running rich. It could be a leaky injector. For hard starts on a warm engine, it could be that the cold start injector is leaking or the cold start switch shorted. Before you try to start when the engine is cold pull the connector from the cold start switch and see what results. If it starts easily then there is the problem. If not move on to test the cold start injector.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
[This message has been edited by Dennis LaGrua (edited 10-11-2018).]
Well I went nuts and took the plenum off and tested for leaking injectors and sure enough found the little (&$(*&(#)! Hopefully this is what is causing the hard starting when warm. I think I will replace the regulator while it is apart. Don't really want to do this again. The question I have is should I just replace the one injector and put orings on the rest or send them in to be cleaned and tested etc. Thanks Dennis for keeping it focused and really finding what the hell is what.
Well I went nuts and took the plenum off and tested for leaking injectors and sure enough found the little (&$(*&(#)! Hopefully this is what is causing the hard starting when warm. I think I will replace the regulator while it is apart. Don't really want to do this again. The question I have is should I just replace the one injector and put orings on the rest or send them in to be cleaned and tested etc. Thanks Dennis for keeping it focused and really finding what the hell is what.
Hard question to answer but cleaning and flow testing usually clears up the problem with a used injector but think about how many times they opened and closed during the course of their 30 service. For an economical fix, I would replace the one leaky injector and the fuel pressure regulator. A friend just had his fuel pressure regulator go probably from age and the effects of E10 gasoline that's popular in this region.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
That's what I did. I got a new injector for the leaker and will put new o rings on the others. Would like to get the others cleaned and serviced but I am going to take a chance that the others will be ok for awhile. Will replace the regulator too. Hopefully all this clears up the hard starting. Can't wait to get it back on the road. WINTERS COMING! By the way Dennis, you got pictures of those beasts?
------------------ FIEROBUG!!!!!!!!!!
[This message has been edited by fierobug (edited 10-16-2018).]
