K, my car went down a few weeks back due to the factory fuel pump finally taking a crap. I have a new pump installed (it's an inline Trick Flow pump, I removed the old pump, installed stainless steel filter and tube that goes down into the tank, new pump is mounted up near where the tank pressure line connects). Car starts up fine, idle comes up, idles for a few seconds and then idles down and shuts off. Before the car died I had a code 34 for the MAF voltage low, but the car still ran fine. It does this no matter if the MAF is plugged in now or not. Do you think the MAF is finally shot? I still get the code, it will start up with no engine light, light will come on and seconds later it dies. Any help would be great, this is the 2.8 in my 86' Firebird.

 

I would think that you should start with the MAF.....if you have a code for it then something is wrong with it. I would find out the test to confirm that the maf is bad. Probably in a repair manual. I can look it up for you if you don't have one.

 

I have a Haynes manual, it just says what code it would throw if it fails but doesn't show a way to test it. I'm thinking it's the MAF too

 

Well, I checked on identyfix....(online professional mechanics website I have access too).....It said code is actually for a MAP, manifold air pressure. Says low voltage/high vacuum. THis website also tracks common repairs by different people....most common repair is the MAF sensor. (don't know why it says MAP bad, and repairs say MAF, maybe typo or the MAF is affecting MAP) I would say it IS the MAF....based on everyone's else's repair info. I would give you the testing proceedure, BUT, the one I have requires the use of a scantool to test. You could take a chance and replace the MAF and see what happens. Sorry, thought I could help a bit more. Maybe someone else here knows at home testing procedure.

 

I'm gonna swap the maf burnoff relay tomorrow and see if that helps at all then try the maf. Thanks for your help

 

You don't have a MAF burnoff relay. That's for V8 engines that have the hot-wire MAF. And codes 33 and 34 are for both the MAP AND MAF sensors, depending on the application. Pre-90, it's for the MAF. Post-90, it's for the MAP (if it's an F-body). There ARE cars out there that have both. Our cars aren't any of them, as those are mostly OBDII.

Swap the MAF relay with the fuel pump relay and see if that helps. Also, remove the sensor and look at the film inside so that a light is reflecting off of it. If the film appears wavy, get a new one. The film is supposed to be COMPLETELY FLAT for the sensor to work.

:edit: BTW, code 34 means the sensor is putting out a low voltage (or none) and shows low air flow, not high vacuum. There is also a MAF fuse... Located next to the inline fuse for the fuel pump and ECM, bolted to the frame rail behind the pass side headlight. It's the one with the red and black wires coming out of it (actually, the black wire has a red stripe, but it usually just appears black).

 

Well I have 3 relays on my drives side firewall bracket. When I looked up relay's for the MAF at NAPA for a V6 it gave me 2 parts numbers, so did I buy an extra relay for something else? On my bracket for the relays I had two relays on the front and one on the backside. One is the fuel pump (which I now have an aftermarket relay wired in) and then the other 2. The fuel pump relay swaps out with the relay mounted on the back of the bracket but not the other one. I also picked up a MAF, figured I'd replace it all while I'm in there, $65 for a MAF with a warranty wasn't a big deal I don't think for a 24yo car. The inline fuse is good, checked it already. There are 2 fuses in that area, both 20a and both are good.

 

K, I replaced the MAF and the MAF relay. My code is now gone but the car still runs like poo. Starts, idles up then dies, if I give it gas it stutters then dies or if I ease into it I can get it up and once it's around 2.5-3K I can hit the throttle and no problem. If I keep it revd for a minute or so it will then idle fine but doesn't want to accelerate/rev smoothly. I've replaced the MAF, MAF relay, fuel pump, fuel pump relay, fuel filter spark plugs, PCV valve. I have new plug wires that I'm gonna try tomorrow and I'm gonna pick up a new cap/rotor as well. The car was running fine before the fuel pump died about a month and a half ago. I had a code 34 but it still ran fine. The only thing I changed was the fuel pump. The pump has over 13v when I check it at the pump with my multimeter. It sounds like a timing issue or ignition issue now but what could be causing it that wasn't there before? I'm gonna see if Autozone has a Fuel Pressure gauge I can use and check to see if I have good pressure at the fuel rails.

 

Update!: Took the car down to the gas station, put $14 bucks in her and drove around and she runs great now. Maybe the computer needed to relearn idle and such? I had to rev it for a few minutes to get it to idle then putted my way down, but once I threw some gas in her and left the station she was running like a champ. No codes anymore and runs great, got up to 75 on the highway no problems. The true test will be tomorrow morning, see if she fires up without issues lol

 

wow congrats I'm having the same problem as you. I'm debating about changing out the fuel pump. Do you think changing out the fuel pump made a difference?


Thanks and good to hear your camaro is running....

 

Well my fuel pump was dead so I HAD to change it. I waited a month for Thunder Racing to send me my Racetronix kit (guess racetronix was backed up or something) and finally gave up and bought a Trick Flow inline pump and while I waited for the pump to get here I put everything else back together. I got in it this morning and she fired right up, idle'd a tad rough but not bad and never sputtered once when I took off. Drove about 30 miles or so on the highway and in traffic today and no problem. Idle did hunt up and down about 250rpm or so at a stop light once, but I think that was from my AC compressor kicking on/off.

 

Thats cool man. If you dont mind me asking where and how much did you get your fuel pump for? I was just going to get one from autozone they run about 80.00 or so.

 

My inline trick flow one with the wiring and relay cost me $99 shipped through Summit. I did have to purchase a filter to put in the tank where my new pickup tube is and I had some high pressure fuel injection hose already but if you don't you'd need it to make your connections. I flared my stock lines where I cut them and slid the high pressure hose over it and onto the pump. 2 days of driving and not a single drop leaked.

 

Thats cool. I was told that there was not much difference from stock fuel pump and after maket pumps.....

What do you think? and how long is the warranty on your pump.....

 

I'd have to look at the warranty card. The difference in the pumps depends on which kind you get. Say a Walbro 255 is only like the stock pump in "design". Where it sits in the tank with a "sock" at the bottom to filter incoming fuel and it sucks fuel right from the tank. It's output is well above the stock pump. My trick flow pump is a higher output than the stock pump and should be good to around 500hp according to reports. I ran it through a calculator and with the right fuel pressure, injectors, and BSFC, it should support that no problem.

 

don't know what happened here... post is below...

 

I'll give you a hint the next time something like this happens (and more than likely it will since I'm willing to bet you didn't get an OEM MAF). First, there is only 1 relay for the MAF as our V6 engines don't have a burn-off relay because our MAF sensors are completely different from the V8 ones. The relay interchanges (swaps) with the relays for the fuel pump and coolant fan. Second, if the engine starts acting up again, remove the MAF and look at the film inside against a light as though it were a mirror. If the light test shows that the frequency film is NOT completely flat, you need a new sensor (mine looks like a skate ramp at the moment, which is why I'm running so rich).

Also, if you were to go to Sears or somewhere to get a decent multimeter, I would recommend one that has the capability for reading frequency in hertz. To test the MAF, put the test probes between the middle wire and the black wire. The frequency at idle should be around 32Hz. Any higher, and something's screwy.

Oh, and also, the 85-89 302 ECMs don't require an idle relearn cycle... The later 730 and up do, however.

 

I have a good multimeter, and it does read Hz, I'll have to check that out. When I looked up the MAF relay's it showed 2 but in the parts store but I'm betting they "condense" it to the make/model and not just the engine. I returned the relay that I didn't need, I've had multiple TPI cars and wasn't sure if these were different at the time, the MAF does look different though. As far as the relearn cycle, I trust ya since I'm not familiar with the V6 electronics, but it did "fix" itself after driving for a few minutes. Few days now and about 200 miles with no issues. I swapped the relay originally and nothing. Code stayed even after disconnecting battery and still ran crappy. Changed the MAF and went ahead and put the new relay in too and it works great. My MAF is a reman'd factory unit. Looks just like the one I removed in every aspect. This time next year the car will probably be running in SD off a Megasquirt so I won't need to worry about it lol. I did the light test and it looked wavy before.

 

Yep, that's the best way to tell if it's bad if you don't have a way to read the output signal.

Glad it works for you. Now I need to do the same thing...