lgoodson@pacbell.net Posted November 26, 2009 Share Posted November 26, 2009 Here's another question. Lately this LT1 is gotten to be a little hard to start the first time each day. After that it fires right up and runs great. But when I try to start it, it pops back through the TB and sends smoke or fuel into the air and I fight it for about 3 to 5 minute and finally it starts. What I notice is that if I keep my foot off the pedal it will start better and when it does it starts at an idle. It is, at this point, flooded and I have to clear it out and then it runs fine. The Helms shop manual for the engine says to check the fuel pressure which I have and it is right where it is suppose to be, 41 to 47 prior to start and 3 to 10 lbs lower after starting. It's correct. But it acts like, with all the cranking I have to do to start it, it is flooded Is anyone out there a fuel injection expert? Next I am going to test the MAP and the coolant temp sensor which I guess causes hard starts according to the manual. The funney thing is that it started fine before installing a new AutoMeter Tach. Then it dsat for 3 months and now it won't start when cold and it's not that cold. Any ideas???? Thanks Larry Quote Link to comment Share on other sites More sharing options...
deja Posted November 26, 2009 Share Posted November 26, 2009 Take a look at the temp sensor, the one that screws into the driver side head right above the number 1 plug. That sends info to the PCM and allows the PCM to send info IAC to the like a choke. Make sure your throttle plates are not set too tight. You should never have to push on the gas pedal to start these engines. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 26, 2009 Author Share Posted November 26, 2009 The sensor on the head is for the Temp gage. The temp sensor on the LT1 is plugged into the waterpump. That is one that needs to be checked but you need a Tech 1 which is the GM test apparatus. Not sure what throttle plates are but nothing has changed since before I installed the Autometer Tach when it was starting fine. I push on the throttle by force of habit but I am trying to brake myself of that habit. Use to carburation. Thanks for the help Larry Quote Link to comment Share on other sites More sharing options...
deja Posted November 26, 2009 Share Posted November 26, 2009 DOH! You are correct the PCM sensor is in the WP, no clue what I was thinking. Sounds like you need to rethink where you have the tach connected. Certainly sounds weird that that could affect cold starts but if its that last thing you need maybe disconnect it and see if the problem goes away. BTW http://www.eficonnection.com/eficonnection/lt1_pigtails.aspx has a pigtail for the black coil connector with 2 wires instead of the 1 we have. I think the 2nd wire is for the tach on TPI cars but I could be wrong. But it might be worth investigating. Quote Link to comment Share on other sites More sharing options...
deja Posted November 26, 2009 Share Posted November 26, 2009 I found this on a pontiac website: Coolant temp sensor can cause a problem if its not telling the PCM the engine is cold. As indicated in the post above, the PCM richens the A/F mixture for cold starts, the same way a "choke" richens the mixture on a carbed setup. If it only starts hard in cold weather, check the coolant temp sensor. If it always starts hard - cold weather or hot - it might still be related to the coolant temp sensor, or it might be a problem that only shows up when the PCM is controlling the engine in "open loop". That's how the PCM controls the fuel when you first start the engine, not adjusting the pulse width based on the feedback from the O2 sensors. After 3 minutes or so, the PCM should go into "closed loop". In order for that to happen, the coolant needs to reach 120-140degF, the O2 sensors need to be hot enough to function, and a timer times out. Once its in closed loop, the short term fuel corrections are based on feedback from the O2 sensors, and the PCM has more flexibility in controlling the fuel correctly. If the problem is related to "open loop" vs. "closed loop" issues, there's a good chance something if mucking up the long term fuel corrections. To find out it this is the case, you need to put a scanner on it, and pull the long term corrections (aka "BLM"s) out for as many of the fuel control cells as possible. Might want to take a look at the air-fuel control section of my online scanner writeup to understand how all this works. http://members.aol.com/InjuneerZZ/ScanMast.htm And this one on a Camaro board: Putting your foot on the floor while cranking puts the PCM in "clear flood" mode. The PCM significantly reduces the fuel flow. That would indicate its either flooded before you turn the key (leaking injectors), or the PCM is setting a too rich cold start A/F ratio. I've seen that caused by a faulty coolant temp sensor. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 28, 2009 Author Share Posted November 28, 2009 deja, Thats quite a post, Thank you. I will study it and the links you gave me, but here's an update. The car hasn't been started for a couple of days but today I cut the wire from the negative terminal of the coil to the tach just to see if it would start better, Guess what? It fired right up without any hesitation so the tach must be grounding out the coil but why would it run normally after it has been started? Either the coil is shorted or it is not? The true test will be if it starts up good tomorrow, When I installed the tach I combined all the ground wires together. There is the Tach ground, 2 signal grounds and 2 panel light grounds, I wired them all the stock harness connector which has a harness ground to the system. Thats a lot of wires. Could these grounds wired the way that I did be a problem? What do you think. By the way it is a Auto Meter Phantom Tach so it shouldn't be a problem. Quote Link to comment Share on other sites More sharing options...
deja Posted November 28, 2009 Share Posted November 28, 2009 I used a TransAm gauge cluster in my car so I was able to use the tach signal from the PCM. On the black (bottom) coil connector on the LT1 there is only one wire +12v (pink) On that EFIconnection pigtail I mentioned there is a secand white wire which might be the tach wire. The TPI engine uses the same coil as tha early LT1s. You might try finding a schematic for the TPI tach to see how that is hooked up. I don't see why the grounds would be a problem as long as they go to a good ground connection. But Datsuns are known for having grounding issues. You might want try taking all those tach grounds to a know good spot rather than going to the stock harness connector. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 28, 2009 Author Share Posted November 28, 2009 The tach is hooked to that white wire off the pigtail which is where my LT1 harness guy said to put it but the white wire is run through his harness and then connects up to a green/white wire at the fire wall. This wire terminates at the harness connector behind the dash which I have the Autometer hooked to. I don't know if there is anything else along the way that might be tied into the green/white wire that could be causing a problem. I need to find a wiring diagram for the 71 240Z. Update: I just fire it up and it started right up so It has to be the tach that was causing the problem. All I did was cut the white wire. Now where's that diagram? Quote Link to comment Share on other sites More sharing options...
deja Posted November 28, 2009 Share Posted November 28, 2009 Well I guess that is sort of good news. All I have is a 280z manual and I doubt thta is the same as a 240Z. The tach wire on the 280Z had a ballest resitor in series and then went to the ignition moudle....I think. Quote Link to comment Share on other sites More sharing options...
deja Posted November 28, 2009 Share Posted November 28, 2009 You might try sending Bartman a PM. He has a '73 240Z with a LT1 and he is running Autometer gauges. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 28, 2009 Author Share Posted November 28, 2009 Update: deja, since you have been so much help I wanted to let you know how it turned out. Looking at the wiring diagram for this 71, I noticed a tap into the green/white wire that I was using for the tach signal. This tap had a resister in it and then went into a black wire. The tach needed none of that so I ran a new white from the coil to the tach and now it starts fine and the tach works fine. I think problem solved but I won't know for sure until tomorrow morning when it gets started for the first time of the day. Thanks for the help Quote Link to comment Share on other sites More sharing options...
deja Posted November 28, 2009 Share Posted November 28, 2009 Cool! I saw that resistor in my manual (see my post #9). Glad you got it working. Of course now every time you start the car you'll worry, LOL. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 29, 2009 Author Share Posted November 29, 2009 No worries about that but I just found 2 new problems. Harmonic balance hitting on ther rack U clamp. I moved the U clamp over over but there is still only 3/16" maybe between thw ballancer and the rack. I have a 7 1/2 inch ballancer so Iwill probably get a smaller one. I am on my second fan belt. Something is making the inside of the belts wear. Less that 100 miles on it. I have checked the edges of all the pulleys for nicks and found nothing that would break a belt. Any Ideas what it could be.. While I was having fun under the car I also noticed that the pressed in hose bibs on the water pump are leaking so that means drill and tap or a new pump unless you have a better idea Quote Link to comment Share on other sites More sharing options...
deja Posted November 29, 2009 Share Posted November 29, 2009 I just went out to look at the clearance I have on the rack and its about the same. I have never had it hit the rack and I've had 2 different racks in the car. I also have a staock 7 1/2" pulley. No clue on what could be causing your belt problem. But I have problems when I have my AC belt on, I've torn up 2 of them. So far no problems with using just the alternator, AC delete, PS delete belt. Did you get a new water pump before you installed the engine? Tapping the fittings would fix it but that would be a bitch on the car. I doubt any sealer of JB weld would really work. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 29, 2009 Author Share Posted November 29, 2009 No I didn't do any thing to the pump before install but I didn't know I would have a problem. The oil cooler one I saw was bent in a little, I figure from a front end collision so I was hoping it was ok. It's not leaking exactly, just seeping. So far there is nothing hitting the garage floor. The belt thing, I don't know. Every thing looks good but somthings not right. These belts are $32 each and I get less than 100 miles per belt. I move the U bracked that I know the balancer had hit because I could see a nick in the clamp. Maybe that will do the trick. A 6 3/4" balancer from Summit is almost $400. Ouch! Quote Link to comment Share on other sites More sharing options...
deja Posted November 29, 2009 Share Posted November 29, 2009 If you slotted you Datsun motor stands like JTR suggested maybe you can move the engine forward a tiny bit. Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted November 30, 2009 Author Share Posted November 30, 2009 Yea, I wasn't actually the one who sat the motor in the chassis. It was there in place when I bought the car. Not hooked up to anyhting but in there. The PO didn't slot the perches so moving it forward would be a problem at this point. Drive line, exhaust pipes, rear mount etc would have to be changed. The other problem is that the bell housing is almost right up against the firewall. I was going to move the engine when I was installing it but it looks as though doing so would run the headers into the steering shaft so I didn't do it. Quote Link to comment Share on other sites More sharing options...
gvincent Posted December 1, 2009 Share Posted December 1, 2009 Yeah I keep chewing up belts except I only get about 20 miles! They start to fray on the inside. I had made my own bracket with an ac grooved idler pulley and a smooth idler pulley where the power steering pump was. I checked it many times for alignment and will try adding/deleting washers one at a time to see if it will stop. If I can't get it right I'll go and buy the power steering delete pulley that Deja and others have used but am not sure which AC delete pulley actually works without hitting the frame rail. I know Deja used an Ebay one but don't know which one. How about this one? http://cgi.ebay.com/ebaymotors/93-97-CAMARO-FIREBIRD-1LE-AC-BYPASS-DELETE-PULLEY-LT1_W0QQcmdZViewItemQQhashZitem3efa65ac12QQitemZ270488939538QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_500wt_1182 Or this one? http://cgi.ebay.com/ebaymotors/93-97-CAMARO-FIREBIRD-1LE-AC-BYPASS-DELETE-PULLEY-LT1_W0QQcmdZViewItemQQhashZitem2556d4ed42QQitemZ160370584898QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_5235wt_941 The power steering delete pulley was in this thread: http://forums.hybridz.org/showthread.php?t=134479&highlight=power+steering+delete+pulley info: PSC Motorsports (http://www.pscmotorsports.com/) Allen Performance Resources 11468 FM 730 South Azle, TX 76020 Part Number: BK-MB31K LT-1 F-Body Idler Bracket I slotted my mounts so I have no problem with the balancer clearance. I did move the engine forward a little bit. Thanks, Greg Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 1, 2009 Author Share Posted December 1, 2009 I had the same AC delete pully and it was a little tight. I went down to Pepboys and went through there pully selection and found a 5 rib that was slightly smaller so I think I have enough clearance. Maybe not. I got the PS delete from PSCmotorsports. My belt wears out on the inside to but I can't see where it hits or rubs anything. The rack bracket was too close so I moved it and I have a new belt on it again with no miles yet, I'll look at that AC delete situation. If you figure anything out, let me know. Thanks Quote Link to comment Share on other sites More sharing options...
lgoodson@pacbell.net Posted December 1, 2009 Author Share Posted December 1, 2009 I just measured my ac delete pully and it is 2 3/4" bought a Pepboys. I have maybe 3/8" clearance to the frame rail. No evidence that that anything is hitting. Quote Link to comment Share on other sites More sharing options...
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