I was driving along just fine when the engine started running rough and losing power. I made it home but now it's hard to start without a little starting fluid. When it does start it runs okay for a few minutes around 2000 rpm like it normally would before settling down to idle, but then it starts surging between 800 and 1300 rpm and the CEL comes on. I cleaned the IAC and have a fuel filter coming. Pressure is supposed to be between 13 and 17? I want to test the fuel pressure and see if it's the pump. I've read some of the other posts and see there could be a hose issue in the tank. Sound familiar? Any advice? Also, I noticed when I was changing vacuum lines there is a black wire at the base of the decklid about 9" long with a spade end that looks like it could be a ground wire that connects to the cruise control but I don't see a place for it. Does anyone know what this wire is for and where it is supposed to go. Thanks.
I was driving along just fine when the engine started running rough and losing power. I made it home but now it's hard to start without a little starting fluid. When it does start it runs okay for a few minutes around 2000 rpm like it normally would before settling down to idle, but then it starts surging between 800 and 1300 rpm and the CEL comes on. I cleaned the IAC and have a fuel filter coming. Pressure is supposed to be between 13 and 17? I want to test the fuel pressure and see if it's the pump. I've read some of the other posts and see there could be a hose issue in the tank. Sound familiar? Any advice? Also, I noticed when I was changing vacuum lines there is a black wire at the base of the decklid about 9" long with a spade end that looks like it could be a ground wire that connects to the cruise control but I don't see a place for it. Does anyone know what this wire is for and where it is supposed to go. Thanks.
That wire sounds like it could be the deck lid switch. If you ground it does the trunk light (if applicable) turn on?
Tell us a little more about the car. Year, engine, transmission. That will help. The black wire may be the ground wire that goes to the metal plate attached to the underside of the decklid. It's a Radio Frequency Static eliminator ground. Stops spark plug and alternator noise on the radio. 84-87 only.
For a V6 engine, fuel pressure should be about 38-40 at idle. 43.5 not running when the key is first turned on. Not sure about the 4 cylinder pressure. That's why the particular of the car is important, but going by your username, it's an 84?
I have a 1984 SE with the 2.5L 4 cyl. and 3 speed automatic with 115K miles. I bought it 2 years ago to restore and have replaced as many of the vacuum lines as I can see, checked the EGR valve and cleaned the IAC valve. I added some FI cleaner as I had no idea how long it sat before I got it. After I put the new vacuum lines on the idle settled down and I had no problems until last week. I hadn't driven it more than 20 miles since I bought it and was running out the old gas idling the engine and driving around the block every few weeks over the winter. Last week I put in half a tank of fresh 87 octane gas and a few days later is when it started surging and the CEL came on. Is there a way to test the IAC valve? The engine is doing most of the things a bad IAC valve would do from an article I read so I'll prolly just get a new one since they are cheap unless another reason can be found for the surging idle and loss of power. Can you recommend a good brand of inline fuel pressure tester? I like the car and get lots of attention from passing neighbors. I have rebuilt, replaced or fabbed headlight motors, alternator, transmission mounts, ebrake system, rotors and pads, dogbone, bearings, seals, airbox, front speakers & baffles. Still have to do window wipes, mirror motors, front main seal, radio, AC comp., tuck up the headliner and try the p/w trick to make them faster. An LS would be nice, too. All in good time. Thanks for any ideas you have
[This message has been edited by Indyrestoproject (edited 05-06-2021).]
When I suspected my '84 was having fuel pressure issues, I used a simple cheap vacuum/pressure gauge to test it. An inline tester is nice, but it really isn't necessary to have the engine running while the fuel pressure is checked. I just disconnected the fuel line somewhere convenient ahead of the TB and connected the hose from the gauge. The two second fuel pump prime period was enough time for me to determine that the fuel pressure was too low. In my situation, the short piece of hose inside the tank had become detached. I described it all Here.
I have a pressure vacuum gauge but was not sure if it would be safe. I don't have a code reader but I'll ask my Bro in-law if I can use his. I think I can rig something up to check the pump pressure while it primes the system. Very good photos of the pump losing it's connector and the fix. Think I'll invest in an IAC valve anyway. Like I said I have no idea how long it sat before I got it. Kinda would like to take a look in the tank just out of curiosity. Some things on this car show it was well taken care of (Eagle GT's, exhaust header, ignition system) and others show neglect (ebrake system destroyed, crumbling vacuum lines). Nothing a little TLC and some good information like the right spec for submersible hose can't fix. I'd rather be riding down the road instead of walking with the $30 bucks I saved on something cheap. When I think of all the irreplaceable 60's muscle cars that went to the junk yard because someone didn't know how to fix them.....anyway the thread has some great info on sensors and valves and hard earned knowledge. Thanks for now.
[This message has been edited by Indyrestoproject (edited 05-06-2021).]
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Checked the vacuum and it reads 22 psi. Fuel filter is clean. Put on the new IAC vlave and it still surges. Unplugged the MAP sensor and it runs fine but dies when I put it in gear (automatic trans). I'm going to invest in a GM code reader and look for a fuel pressure gauge. Mine only goes up to 9 lbs. If the fuel pressure is low I'll go ahead and pull the tank. Probably not a bad idea anyway. Get the outside powder coated. Armor Shield the inside. What's the best brand of fuel pump? I have a new ignition module to put on. Good to still be able to get spare parts cheap. Plugs and an oil change won't hurt. O2 sensor, MAP and MAF sensors are all that's left to replace? Are there ways to test these? Anything else I can check? Maybe clean out the throttle body? Thanks.
[This message has been edited by Indyrestoproject (edited 05-19-2021).]
Definitely pull the tank. Before you do, get a new fuel pump (ANYTHING BUT Precision brand), and a new strainer. YOu'll probably find the strainer is clogged with crap.
I hooked up a pressure gauge this morning with an inline shutoff valve and a return hose to the tank. I did get some flow through the hose for a few seconds but never got any pressure readings once I closed the valve. After a couple of tries I couldn't even get any flow. I removed the test line and reattached the fuel line to the filter. The engine started and ran for a few minutes but then it started surging again with the check engine light on. I'm going to invest in a code reader today. I can still use the test line to help drain the tank. Thanks for the tip. I'll post results as I go along.
Okay, I'm game. That looks like a highly technical piece of equipment. How would I go about using it and what am I using it for? The guy at the auto parts store (O'Reilly) warned me off code readers too. So......I'm still going to pull the tank. Need to assemble fittings and hose for the inline pressure gauge. My father RIP was a NASA engineer and I have more shelves of fittings and tools than I'll ever use. Even so sometimes I never can find just the right one. Thx.
[This message has been edited by Indyrestoproject (edited 05-20-2021).]
If it IS the fuel pump, make sure to replace the short rubber hose between the fuel pick up and the pump with GASOLINE SUBMERSIBLE RATED fuel line! The regular run-of-the-mill fuel line will deteriorate quickly and you'll be pulling the fuel tank again.
I read the link about using a clip to read the codes so I'll try that today. His link also mentioned the rubber hose, so thanks for that. Depending on the condition I may go with a Carter or just get the GM EP386 kit with the hose. We used to use something called Armor Shield to coat the floors and walls of 3 million gallon gasoline storage tanks. There's another product for regular tanks. Undercoating should work for the outside.
Thanks to Patrick. The code is 44 lean exhaust. I started the engine, it ran fine for a couple minutes then started surging and the CE light cam on. Jumpered the A&B and after the 12 code I got the 44 code a few times before it went back to 12. Looks like there are about 6 or 7 things to check. I can cross off knocking. When I disconnect the vacuum line to the MAP sensor the surging goes away. Not sure if I should disconnect the wire plug too. Will check for resistance on the 02 sensor. It looks like the sensor is on the passenger side down on the exhaust header. I already checked vacuum and it's normal at -22 psi. I use HEET so water isn't a likely culprit. I'm going to invest in an inline fuel pressure gauge just to see what is going on there. So I'm on the right path. O2 sensor is cheap, MAP not so much. THX
[This message has been edited by Indyrestoproject (edited 05-22-2021).]
Indyrestoproject is running again. Can't stress enough I learned never buy anything less than Delco. I found a company in New York to rebuild the stereo and as long as it's up I'm thinking about replacing the seized up a/c pump. I'm on my third temp sending unit. Sometimes it works...and I need a fan switch but if I remember all I could find last time was a non-a/c switch. Thanks and a beer for the house.
[This message has been edited by Indyrestoproject (edited 10-18-2021).]
