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Crusader 270 bogging/stalling at idle

J

junior4597

Contributing Member
Hi - got a situation that I cannot get my head around so I thought I'd send up a post. I have a circa 1987 Crusader 270 that stalls at low idle but does not stall once the throttle is pushed up above 1000ish RPM and runs perfectly under way (this is ONLY the stbd engine - port is fine). Here are the circumstances, things I have done and things I am thinking of doing next.

Symptom - stalls at the dock in neutral running at idle AND when under way at idle speed (I'd say 95% of the time). I have to bump up the throttle when I hear it sputter and begin to stall, when I do it's OK or else I am too late and it stalls and needs to be turned over again. When I crank it over sometimes it starts right up but sometimes I have to push the throttle up over and over to juice some fuel and it usually sputters when it restarts. When I am under way and over 1k RPM she runs just fine. When I put her in reverse gear to back into a slip, she usually stalls (on the stbd engine only).

Things I have done
  • Rebuilt the carburetor, in fact both carbs (Rochester Quadrajet 4 barrel). Replaced needle, seat, float, check ball, power piston spring, seals, gaskets, accelerator pump, filter cartridge. Kept original jets, primary and secondary rods. Cleaned and blew air throughout. Set float to 9/32".
  • Replaced both Racor fuel filters (no in-line filters, those have been removed)
  • Replaced both anti-siphon valves at the tank (single tank)
  • Blew air though full fuel line
  • Swapped fuel lines from port to sbd engine and vice-versa to test (IE port fuel line feeding stbd engine)
  • Swapped carburetors, issue stayed with the stbd engine
  • Set idle mixing screws via vacuum gauge, roughly around 20-22 inches of vacuum
  • Set idle screw to 650-675ish RPM at idle speed and underway (used electronic meter) per Crusader specs
  • Adjusted choke thermostat, works perfect starting cold and when engine is at operating temp
  • Tested fuel pressure from mechanical pump, got various readings from 5, 6, 8 but typically 5, I also tested port fuel pump and got 5's (crusader manual says between 5.2-6.2)
  • Replaced stbd mechanical fuel pump thinking this is all fuel related
  • Timing is set to 10* btdc

Still have the issue

Things I am going to try next and am looking for thoughts and maybe some suggestions. I was convinced this was all fuel related - my logic suggested at lower RPM the carb bowl would drain and not load quick enough due to a fuel delivery issue (pump diaphragm, clog etc) and would stall. Only when I goosed the throttle or bumped it up was I thinking the pump was filling the bowl to prevent stalling, maybe a weak diaphragm or something. Didn't appear to be that simple.

Trying next (moving on to electrical)
  • replacing the coil
  • replacing the condenser ( I have points and not replacing them cause they are still good)
  • Points are set to a dwell angle of 32 (calls for 30)
  • Replacing wires
  • Replacing plugs
  • Would like to replace the whole distributor for electronic but that's a different story (cant use a conversion kit on this mallory model)
  • Checking all grounds, connections and voltage from starter to ballast resister to coil etc for anything loose

Hopefully someone with more knowledge than me can review my logic on the fuel troubleshooting to see if I missed anything and then validating that moving on to electrical is the most sensible next step. Anything else I should be checking on? I'm sure I am missing something and figured this is a good place to get some suggestions!

I reviewed some other posts around stalling engines but none seem to be similar to my situation.

I welcome any thoughts and thanks in advance!
 
how many hours are on the engines?

any recent compression test values?

Any maintenance history you can share?

are the plugs running rich at idle?

have you checked the distributor to make sure the timing advances with RPM?
 
Probably some poop in the idle circuit.. Pull the carb off, blow out all the idle passages with compressed air and try again. I hesitate to suggest using wire or other poking devices as these can damage the passages if used wrong. Also have a look at the idle jet as it can clog if it sucks any debris up. Seems that several people are finding bits of teflon tape in their float chambers this year, although that seems to be more with old MGs and Land Rovers. Yeh when it's off idle it runs fine cz it's not using the idle circuit any more.
 
Makomark, I have about 1100 hours on the stbd engine and I have to assume those are accurate and original. I don't have any new compression values except to pull them up from my survey 11 years ago. I was thinking of doing them again to see if they are in line. I'll have to get back on that. Both engines have been pretty reliable over the past 11 years. I've done basic stuff to them and on the stbd in particular the normal maintenance items like tune-ups (wires, cap, points, plugs etc), impellers and now fuel pump but nothing crazy. When I bought the boat it did have a warped head that was fixed prior to the purchase but have never had any issues after that from over heating etc. I did pull the plugs and they did seem a little black and that engine was probably running rich at some point but as I stated I will be changing them this week. I have looked at the distributor but did not check the advance as I figured this was an issue at idle but I can do that. I have had issues with those distributors only in having to tweak points, dwell and general upkeep, I'd love to pull them! I'll have to look back at some other posts to get the advance numbers and test with my light. Other than that no other real issues or major repairs on that engine, or the other.

o2batsea, the carbs have been rebuilt, soaked and blown out at that time. Granted I did them but I've done a few and feel confident but I understand you never know. That said, I've swapped the carbs and the issue did not follow so unless I'm missing something I don't feel its a clogged carb. The stbd carb is now on the port engine and vice versa and the problem is still with the stbd engine.
 
Well if it's not fuel it's spark. When't the last time you did a tune up? Points condenser rotor cap plugs and wires. Be sure that you have the wires on in the correct order. Yes I know but it can happen.
 
1000 hours is typical service life for the top end components....they could be a contributor - the compression test will shed light there....

the engine has to be in good mechanical shape to run correctly....

the timing advance mechanisms under the breaker plate, inside the distributor, are usually neglected....it the timing doesn't advance smoothly with RPM, its a good indicator attention is needed there...worn distributor shaft/bushings can cause similar timing anomalies...

the other thing is idle speed - did you set it once warmed up and in gear?
 
Just replaced the ignition coil and that didn't help any. I will be replacing the rotor, cap, condenser, wires and plugs soon. I'll probably replace the points but they look just fine. I'll throw the light on to monitor the advance curve as well. Again this is in low idle, some times with or without load. I guess I'll also have to perform a compression test to see what the numbers look like. I did adjust idle speed at operating temperature and underway with a load at idle speed. I do know the elbows and risers need to be replaced but it's not overheating and I can't imagine how that could have anything to do with the issue, just throwing that out there as part of maintenance items. It sounds so much like fuel delivery that I am going to start it off of a separate tank of fuel to see, who knows. I did read that a faulty tachometer can cause an engine to stall, any validity around that and should I pull the leads off to see if it helps? I'm grasping at straws here.......
 
tachs can go bad and keep the points from working....it won't hurt to try - remove the grey wire at the coil and tywrap it back...

may also want to check the ballast resistor connections....they are known to corrode and cause problems, too.

agreed, the riser are likely not contributing to the problem...and - as long as you are careful and pay attention - it wouldn't hurt to use a separate fuel supply for testing purposes...

you can also try pulling the back two spark plugs if it cuts out while moored in the slip....if the plugs are wet, would indicate too much fuel at idle...another indicator is a sheen in the exhaust....too much to burn...

also, when you did the idle mixture adjustment, did the needles have positive control? where did you wind up setting them?
 
Update - I tried pulling the tach wire off without any success so that's out. I also pulled the back two plugs, they look a little black so I will be changing all of them but they were not wet. As far as the mixing screws are concerned I turned them out 2.5 turns and then used a vacuum gauge to measure the highest point of vacuum (and used my ear). Ultimately I was able to get to 21 inches of vacuum, not sure of how many turns that ended up being but at 2.5 turns the gauge read only around 19 inches so I was able to gain a bit more vacuum by going in a bit (I believe). I also have the compression numbers below, I think they look good as they don't really differ from the test performed 12 years ago. This all said, my next steps are to pull all the ignition wires to clean and reattach as well as replace plugs and wires, cap, rotor, points. That's my last hope but I'm sure I'll figure this out soon!

STBD #'s
1 - 175
2 - 180
3 - 170
4 - 180
5 - 165
6 - 180
7 - 170
8 - 175
 
compression numbers look good so I'd say the engine is in decent mechanical shape...

swapping carbs with same result (and new pump) suggests electrical...so I'd say keep going down that path...

would still check timing advance for smooth and consistent operation...and make sure there is no sheen in the exhaust...and make sure the ballast resistor connections are sound (solid with no corrosion)...
 
Got it!!!! Finally ended up being electrical after all. It's funny how some symptoms seem like one thing, lead you there, and end up being something totally different! I was convinced it was fuel related but after the fuel pump replacement I was suspicious. Resolution - I disconnected all wiring from my starter to ballast resister to coil to distributor, cleaned the connections, reattached and voila! There was also a bare ground wire inside my distributor that looked like it was touching the inside of the aluminum housing that I moved away but since I did that AND cleaned/reattached I am not 100% certain which resolved it but it was certainly electrical. Funny thing is, my electrical connections were not loose nor corroded but I decided to do it anyway and there is was - runs like a champ now at low RPM! I won't forget that lesson but necessary steps to get to the end result!

Thanks for all the advice Makomark! It's good to get confirmation and validation as you take the many steps to troubleshoot! Great site to talk things through....on to boating now!
 
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