How to Measure and Diagnose Fuel Pressure on Tuned Port 305 / 350 3rd Gen Camaro / Firebird

[@BlownInterceptor71]

I had an 83 Z28 and an 87 IROC. I got lots of people that wanted the 87. Then I moved to a 2000 Z-28 with a Vortech V9 Blower. That car was a beast. Stock boost was 6 lbs. of boost, I learned to tune it HP tuners. All in all, I made close go 600 rwhp. I was able to copy the high-octane table and paste it over the low octane table. Now I had a 2.5 pulley pushing 16psi of boost. Took 1 or 2 degrees of timing, just because. Didn't really have to. Plus, I was running alky injection, I saw no detonation, so added a bit more timing. Race gas only 110 octane, adjusted the A/F to near perfect. 600rwhp back in the 2000's was a lot. Damn, I was I still had that car. Alky injection was key. One thing I will never understand, Vortech had the cooled lines through radiator mixing with the air to water aftercooler. That puzzled me, so I decided to make it a closed system, my intake dropped temps dropped, why they did that, I have no idea?

[@bitsofwisdom460]

That sounds like a great package with lots of power. Alky injection is a great help with detonation. Back in the '80s when 91 octane was the best I could get for my 428 Mustang, I had a Holley system that I ran 50 / 50 water alcohol to keep it under control. Regarding the cooling lines going through the radiator, there may have been some issue running at very cold temperatures. While it likely sacrificed some power, it may have helped engine performance when it was cold.

[@cart-wheels]

You've been reading my mind. A fuel injector pulse tester just arrived. I've got new injectors as part of preventative maintenance for my car that sat for years and had the original injectors. Now I'm diagnosing several issues that impact it running correctly. Can't wait to watch your video. Thanks!

[@bitsofwisdom460]

You're welcome!

[@JohnCRV]

The information in your videos are very valuable. I’m learnIng a lot about the 5.0. I want to thank you for that. I’ve noticed many ask you questions and your reply is impeccable but no one I’ve seen even thanks you, sorry but that’s just wrong! Anyway, that’s my 2 cents. My son and I are getting ready to revive his high school car, a 1992 Camaro z28. Been sitting in his garage for 10 years. It stalled and never started again for all those years. We have determined it was a bad pump and ordered everything . Tank, pump, injectors, filter , regulator….. and more. Hopefully we are successful. Your videos will definitely be of great help and we will be filming as much as possible. I wish we had a service manual like you have but if we run into a bind we can always ask you. LoL Thank you again for your valuable videos, we will be watching the whole Camaro playlists.

[@bitsofwisdom460]

Thank you for your kind words. I appreciate the feedback. It sounds like you have a good project with the Z28, and yes it sounds as if you'll be going down a similar repair path. I hope your engine is in better mechanical condition than mine was. Used service manuals are still around. I point people to someone that once worked with me at GM. For many years now, he runs an online store that sells manuals for cars. Books4cars.com The last time I checked, he had a good selection for 3rd Gen Camaros. And if you have questions, just ask. If I can answer, I will.

[@JohnCRV]

@@bitsofwisdom460 Thank you for the reply Dan. We're ordering parts and some tools we dint have. Just changing the spark plugs will be a project with this car, since it has the bigger headers LOL. We already dropped the rear end and will be installing the new tank and new pump first... It will be a slow process since we only have weekends and with the holidays it will be a while. We're not in a big rush and want to make it fun anyway, hopefully. We appreciate the link for the online manuals store. Hope you enjoy the holidays.

[@mikebruegger8654]

Mine leaks down as well just like yours. I believe it to be normal. My car had problems starting that I spent lots of time trying to corner the issue. I replaced lots of sensors and did all the checks in the sevice manual. Ended up being the remote pick up coil that failed intermittently. Easiest fix was a distributor complete with pick-up coil and module. Now it starts like a dream..... 😊

[@bitsofwisdom460]

Thanks for the feedback, that's good to know. And yes, the intermittent electrical issues can be a great challenge.

[@sergiocantu1000]

where is the remote pick up coil located? is it the ignition module inside the distribuitor?

[@johnritchie2607]

Excellent video

[@bitsofwisdom460]

Thank you very much!

[@Turbogn87]

Yesss my trans am does the excact same thing, you shut it off it might take several hours but it does drop, I agree, I think just a little seepage for an almost 40 year old car is more than perfect. Doesn't seem to hurt or flood anything so i dont worry

[@bitsofwisdom460]

Yes, agreed. If I thought that it was an injector dripping, it might be an issue because you could foul a plug, have smoke on start up, or have gas dilution in the oil. No sign of that, so no worry. I was a little surprised when I rebuilt the regulator and fuel rails that it appeared that the regulator seal was metal to metal. Those can be hard to seal 100%.

[@iborges1794]

Great videos,,, we are still dealing with fuel pressure not staying up but this videos helps greatly... Where did you get that manual.. What is the name of it, it's looks much more informative the the Chilton or Haynes manual.

[@bitsofwisdom460]

That is an old GM Camaro service manual. I picked that one up on eBay. It is a looseleaf version like a dealership used so that it could be updated. An alternative source is: books4cars.com/ The owner used to work with me at GM years ago. Last time I checked he had a variety of GM Camaro manuals from that era.

[@danielpineda4352]

Just the video I was looking for thanks BOW

[@bitsofwisdom460]

You're welcome, hope it helps.

[@bencramer5458]

Exactly what I needed thanks

[@bitsofwisdom460]

You're welcome. Glad it helped.

[@rickkimble8634]

Nice info

[@bitsofwisdom460]

Thank you.

[@budsodalsky]

Very informative! Thanks for the info on HF check tool. Now I know they're ok and buy one. I have a question: what do they call the camaro six cylinder's injection ? Tuned Port? I know 6 cyl had throttle body - but what about the ported one?

[@bitsofwisdom460]

The Camaro 2.8 and 3.1 at least 1985 and beyond were called Multi Port Fuel Injection. I have a pdf of a 1985 brochure and "Multi Point FI" is the logo on the intake system. You can find more specs on the GM Heritage site. They have information packages posted for download for many models. It was down for a while, but they have it back running with new links: www.gm.com/heritage/archive/vehicle-information-kits

[@nordichoonigan5726]

I could use your knowledge. I’m on the verge of doing a carb swap to get over this issue. I have a 1990 Trans Am GTA 5.7 TPI. It’s not getting fuel. I don’t really hear the pump priming. It gains pressure while cranking. I’ve replaced the pump with a quantum pump, a new filter, new injectors, new relay, new fuse. It starts up for a moment with starter fluid then dies. I don’t know what to do next. Like I said, I’m on the verge of doing a carb swap to get over the tpi. And help/tips would be appreciated!

[@nordichoonigan5726]

Forgot to mention I’ve also replaced the fuel pressure regulator.

[@bitsofwisdom460]

Have you measured fuel pressure to see if it is correct? If you don't have sufficient pressure, then that would give one path to work. You have worked most of the fuel system. If you're not getting sufficient pressure at this point, I would be checking the wiring to the back of the car to be sure it is getting full voltage and that the ground is solid. ECM will give a code for low voltage, but it is sensed at the front of the car near the relay. If you are getting pressure, there are several possibilities: -Check ignition, weak spark can sometimes light ether when it won't light gas. Alternatively, excessive rich mixture / fouled plugs can be hard to light. -Check the system with a scan tool and see if the sensors are reading correctly for a cold start. MAP ought to be atmosphere (14.7 psi), temp should be right. Throttle position should be correct. -Try starting with higher throttle - 30 to 50%, if that doesn't work try 100%. There is a "clear flood mode" that takes the fuel to zero at WOT crank to clear a rich condition. -Are the injectors getting a good signal? It might be a bad driver in the ECM. But the injectors run off of two driver circuits and you would expect at least half the injectors to fire and the ECM to set a code. I would pull the plugs after trying to start and see if they are wet or dry. -Check EGR system to be sure the valve is closed.

[@nicholasesposito9754]

Can I run a higher pressure? Plan on running a larger TB

[@bitsofwisdom460]

You could run a higher pressure with an adjustable pressure regulator, but I don't know if changing the throttle body would necessarily require higher fuel pressure. I don't have experience with that on this engine, but the basic thought is this: If you provide more air (higher manifold pressure), the speed density system ought to command higher duty cycle on the injectors, and until you exceed the capacity of the injectors, current fuel pressure should be fine. You would need to watch for signs of lean mixture. The fuel calibration in the ECM is based on the standard fuel pressure. It would be good to consult with someone who does ECM tuning. The injector flow spec plus fuel pressure plus ECM calibration would be required as a package.

[@jesseortiz8829]

So a question . I hv a 91 z28 L98 I rebuilt the whole motor and fuel system . New injectors new regulator new pump and tank . Car started and ran great . About 5 months ago pump went bad so I replaced again and ran good again . A couple weeks ago it start hard and quickly shut down . Plugged in fuel gauge and went up to 42 psi but loses pressure to about 15 psi in about 20 mins . Is that indication of regulator or bad check valve?

[@bitsofwisdom460]

The manual indicates to key up and see the pressure get above 40 psi then the pump will stop, then pinch the feed hose to rule out leakage back to the the pump and feed system. If ok, pinch the return hose to rule out leakage at the regulator. The third option is a possibility of a leaking injector that might be seen by checking for a wet spark plug. There is also a process in the book to remove the fuel rails and pressurize them to inspect the injectors for leakage. Now, that said, there can be some amount of leakage in a normal car. Mine does not hold perfectly over longer times. The trouble trees don't indicate how long the pressure should hold. So from a practical standpoint, if the system holds pressure for a few minutes, the pump ought to be able to maintain pressure in the system at idle for a start.

[@kmas8229]

Hey there! What service-manual is that and where can I order one? Great video, really helpful and easy to understand and comprehend! Hope you're doing good!

[@bitsofwisdom460]

Yes, I am doing well, thank you. Glad the video was helpful. That is an original 1985 Camaro Shop Manual. It's the loose-leaf version that I believe was targeted for dealerships so that it could be updated through the year. I picked that one up through eBay. It took some searching. There were also some bound copies out there and I saw some offers with the manual on a CD/DVD, but I couldn't tell if those were "official" GM information.

[@kmas8229]

@@bitsofwisdom460 Hello again! Glad to hear you're doing good! I guess it could be hard getting one of those for my 87. Is there an other manual you'd recommend getting? Already got Haynes, but the content in it is kinda lacking compared to other manuals, especially when there so many different engine options and trim-packages for a model.

[@bitsofwisdom460]

@@kmas8229 Original GM manuals are the best, and they are readily available as used through various sources. One place that you might try is books4cars.com. I worked with the owner, Alex, at GM many years ago. He started with rare manuals for European cars, and has expanded to a rather wide range. As the business grew, he left GM to run it full time. I checked this morning and he had a good selection of Camaro manuals.

[@kmas8229]

@@bitsofwisdom460 Hello again! Thanks for the tip, appreciate it very much! Good for him that he got to do that stuff full time, I guess he has alot of "gold"! Old articles, brochures, service-manuals and such are fascinating to look and read through. Hope you're having a great day!

[@bitsofwisdom460]

@@kmas8229 You're welcome! It's actually interesting how Alex got his start. He was interested in various European cars that were imported to the US in low volume. He had one or two as I recall. He was having difficulty finding service manuals for them here in the US. We sent him to Europe on business for vehicle development. He was surprised to find manuals there, but the companies weren't interested in selling to the US at retail because of the low volume, one at a time. He found places that would sell and ship to him in the US for resale, and it grew from there.

[@ttwgarage4049]

My camaro won't start no more it's reading 15 psi on the gauge but need to do quick the relay I just bought a regulator gonna change it see what happens

[@Miggy0089]

I like you book for the iroc where do you find these? I;ve been looking for a good book that will have good information. i'm truing to figure out my iroc is. After i changed my fuel pressure Regulator Diaphragm is been dieseling. The original one was leaking and was not doing it. after a new one now it does it. I do have and adjustable cap tho and tried playing with it but still...

[@bitsofwisdom460]

I bought this one through eBay. It is the loose-leaf version that usually was used by dealers so that they could update during the year. The same information is available in the bound version. You can probably find one on eBay or try books4cars.com. books4cars has many manuals and other documentation.

[@nicholasesposito9754]

Have a 91 z28 5.7 .

[@larrycutler9196]

1989 camaro didn't come out with a cold start injector

[@bitsofwisdom460]

Yes, that is correct. With the exception of that, most of the diagnostics for fuel pressure ought to be the same.

[@nicholasesposito9754]

My fuel pump is running after I turn car off .caused my batt to go dead.

[@bitsofwisdom460]

You likely have a bad fuel pump relay. On the '85 wiring diagram, the relay is fed direct from the battery through a fuse. If it sticks closed, the fuel pump would have power even with the ignition switch off. On the '85, the relay is to the right of the brake booster when looking from the front. I expect yours would be in the same area. The relay plugs in to the wiring harness and bolts to a bracket.

[@boogaloojuly4th]

So what would I need to do if my fuel pump is not coming on?

[@bitsofwisdom460]

There is a relay next to the brake booster. It should be on the right side of the booster as you look at it. It is fed by a fused line that is always hot from battery. The ECM will send a signal to energize the relay when the key is turned on (2 seconds limit if engine doesn't begin turning). The relay sends power back to the fuel pump. If the relay is bad, there is an oil pressure switch that will bypass the relay if you crank long enough to get oil pressure. So, you can have a blown fuse, a bad relay, a bad ECM or wiring, or a bad fuel pump. There is a diagnostic to use a fused jumper to feed power to the fuel pump to be sure it is good. You can hear it. I'm not sure if all years are the same I am looking at the 1991 manual for TPI and it has a chart to diagnose code 54 for low voltage in the fuel pump circuit. I don't know if all years have the code 54.

[@boogaloojuly4th]

@@bitsofwisdom460 your KZbin name definitely is a match for you, I have a 88 2.8 manual, I just got through rebuilding the engine , it's been about a year , but it got done finally, it was starting briefly , then would cut off , not staying on for more then 3 seconds, I could not give any throttle, then I had finished with the charge on the battery and I noticed the bell noise it makes when you have the key in wasn't on, as well as the fuel pump didn't click on, but it was going to start up, I just didn't want to force it , without figuring out a few things ,and I also used a jumper to b&a for the adl like you had said in one of your videos, it's just throwing 12 at me thank you alot for your time I will definitely check that relay out , and see if I can get power to my fuel pump , thank you ,Sir

[@bitsofwisdom460]

@@boogaloojuly4th Your port injected 2.8 should be very similar to the 5.0 /5.7 port injected. I went back and checked 1985 as well. There is a 54 code for low voltage. The ECM has a sensing lead at the fuel pump relay. If you're not getting a 54, the problem is likely the fuel pump or its wiring. If you have a bad connection either in the feed wire from the relay to the pump OR the ground wire from the pump back to the car body, the pump might run slow / low pressure. Either way, if the pump will provide just enough pressure, you might get a start but not be able to keep it running. There is a Pin "G" on the ALDL connector that the manual says can be fed with a 12v fused supply to bypass the relay and test the pump.